Since I did one on techs YOU should research. It's only fair I do one on things you should probably not do as much. The expansions brought alot of balance changes and new techs but just how good are those techs? Also what older techs should you still avoid. Again, good chance I missed more not as useful/useless techs. So if it's not on this list don't get mad.
Anyway no particular order. Here goes
1) Boiling Oil. Are you surprised? Not only is the bonus limited to Rams. You also need to research Murder Holes to kill a ram attacking your castle let alone it reaching your castle to begin with needless to say persians dont get bracer. While it does 9 damage to battering rams. It does 8 to capped and 6 to siege due to Ram armour reducing the damage. You know you're useless when you're surpassed by Yasama towers and Celt Castles. And if your castle is being rammed down chances are you already lost it.
2) Heated Shot on land maps. Since camels aren't ships anymore there isn't much use for this tech. It's not that great on 1v1 water maps either and maybe in the late game water maps you could do it but even then it's extremely niche. What was once an underrated tech is now mediocre at best. It does work with harbours though so there is some saving grace.
3) Madrasah. Well not entirely useless but not useful either. It's very situational as to when you would do this tech. If you're doing the famous saracens monk rush you arent gonna get a castle up for this tech.
4) Orthodoxy. Not as useless as Madrasah but again only viable in 1 tc FI monk pushes. Makes no difference vs Light cav but you do survive 1 extra hit from a Hussar FU attack. Pretty skirm resistant though.
5) Greek fire. You arent really going to have a castle up in a water build on maps like baltic islands etc. By the time one is up it might not even be worth grabbing if your focus changed from water to land. Galleons become a better choice in the end.
6) Panokseon. Okay it's cool Turtles dont need a castle anymore. But to make them remotely viable you still need one to be able to catch up to certain ships better. Very double edged of a tech. Not a tech you're gonna grab even on a BF lake. Maybe in the very late game if you manage to make it there with any resources left to spare.
8) Carrack. Not as useless as the other above 2 techs but not one you'd get in castle age. Maybe to increase leftover ship longevity in imp you can but in pure castle age water fights. Not a huge priority at all and can probably be ignored.
9) Herbal Medicine. Except if you're Aztecs. It's very rare you'll garrison units intentionally for healing purposes when a few monks can do it better. Having army in a building to heal makes them idle. The few civs who could viably use these strat (Teutons/Vikings) dont even get the tech. Although recently I found out castles heal units 2x faster than any other building. Base 12hp/min can go upwards of 48hp/min in a castle with the tech. Still you're better off using that gold early on for something else.
10) Town Patrol. Not to say this tech is bad. Outposts cap at 20 LOS and you can reach near 20 LOS in imp without it. Town watch is far more valuable and usually more than enough. Byzantine should get this tech for free. Is that an unpopular opinion? Probably.
11) Stone shaft mining, compared to other eco techs and given that stone is less common than gold on standard Arabia maps. Usually the first stone mining upgrade suffices. If you urgently needed stone then sure grab it by any means but wood > farm > gold upgrades are generally better.
12) Atheism. Unlike the other Hun tech marauders which is awesome. This tech is not that great. Unless your on standard victory. But for some silly reason, it also adds +100 years to you as well. The secondary effect of 50% spies is nice though. Though I can't think of any reason as to why any hun player would casually bank 15k gold for this tech.
Anyway no particular order. Here goes
1) Boiling Oil. Are you surprised? Not only is the bonus limited to Rams. You also need to research Murder Holes to kill a ram attacking your castle let alone it reaching your castle to begin with needless to say persians dont get bracer. While it does 9 damage to battering rams. It does 8 to capped and 6 to siege due to Ram armour reducing the damage. You know you're useless when you're surpassed by Yasama towers and Celt Castles. And if your castle is being rammed down chances are you already lost it.
2) Heated Shot on land maps. Since camels aren't ships anymore there isn't much use for this tech. It's not that great on 1v1 water maps either and maybe in the late game water maps you could do it but even then it's extremely niche. What was once an underrated tech is now mediocre at best. It does work with harbours though so there is some saving grace.
3) Madrasah. Well not entirely useless but not useful either. It's very situational as to when you would do this tech. If you're doing the famous saracens monk rush you arent gonna get a castle up for this tech.
4) Orthodoxy. Not as useless as Madrasah but again only viable in 1 tc FI monk pushes. Makes no difference vs Light cav but you do survive 1 extra hit from a Hussar FU attack. Pretty skirm resistant though.
5) Greek fire. You arent really going to have a castle up in a water build on maps like baltic islands etc. By the time one is up it might not even be worth grabbing if your focus changed from water to land. Galleons become a better choice in the end.
6) Panokseon. Okay it's cool Turtles dont need a castle anymore. But to make them remotely viable you still need one to be able to catch up to certain ships better. Very double edged of a tech. Not a tech you're gonna grab even on a BF lake. Maybe in the very late game if you manage to make it there with any resources left to spare.
8) Carrack. Not as useless as the other above 2 techs but not one you'd get in castle age. Maybe to increase leftover ship longevity in imp you can but in pure castle age water fights. Not a huge priority at all and can probably be ignored.
9) Herbal Medicine. Except if you're Aztecs. It's very rare you'll garrison units intentionally for healing purposes when a few monks can do it better. Having army in a building to heal makes them idle. The few civs who could viably use these strat (Teutons/Vikings) dont even get the tech. Although recently I found out castles heal units 2x faster than any other building. Base 12hp/min can go upwards of 48hp/min in a castle with the tech. Still you're better off using that gold early on for something else.
10) Town Patrol. Not to say this tech is bad. Outposts cap at 20 LOS and you can reach near 20 LOS in imp without it. Town watch is far more valuable and usually more than enough. Byzantine should get this tech for free. Is that an unpopular opinion? Probably.
11) Stone shaft mining, compared to other eco techs and given that stone is less common than gold on standard Arabia maps. Usually the first stone mining upgrade suffices. If you urgently needed stone then sure grab it by any means but wood > farm > gold upgrades are generally better.
12) Atheism. Unlike the other Hun tech marauders which is awesome. This tech is not that great. Unless your on standard victory. But for some silly reason, it also adds +100 years to you as well. The secondary effect of 50% spies is nice though. Though I can't think of any reason as to why any hun player would casually bank 15k gold for this tech.