This is a great bit of info that should definitely be mentioned in the FAQ or some Wiki page. That was my reasoning also, having already experienced how vastly different Age of Empires 2 Easy/Standard and Moderate AIs are. I've tried playing Easy on Defensive expecting some huge losses, but it was still too easy. Guess I should try out Medium now that I'm more accustomed with the game.

Not really. They're interrelated but not the same. A slow paced game can still be a difficult game. And a fast paced game can still be an easy game. 

Yet another approach might be to set the bot's behavior to defensive (via the cog in match setup); expect heavy losses when you do engage, but at least they're not messing up your settlement and eco.

Well I don't play multiplayer so they're kind of the same thing...

Medium is much more challenging because the bot is allowed to reach P3 and research every tech eventually. At this level, both of you have the same conditions so it's a fair match between you and the AI algorithm. Lower level bots are forbidden from reaching phase 3 or research important techs so they are totally useless, hence too easy. Higher level bots have additional bonuses in their favour but there is no fundamental change to their behaviour, so they aren't significantly harder than the medium bot. With that being said, this is more of a skill issue and AI difficulty issue than train time issue. The train time should match up with the feasible resource income rate of the player. The current values are fine. Lower ones would allow the player to convert their float into reinforcements quicker, which is important in late game. Sometimes I can float thousands of food and wood just by collecting loot from dead enemies. Therefore a conscription_II and conscription_III would be nice to have.  

Sounds like your gripe isn’t with the game pacing but with difficulty. 

I think I played that once, and it did get pretty slow. So slow, I got bored and sped it back up. I will give it another try though and let you know.