The issue with ttm is that because you are forced to fight, and because the field is open, it doesn't really help you in real games.
It's surely good when you don't use control groups and you need to learn how to play bow/pike/cav vs bow/pike/cav, but in real situations, there are so many factors you need to consider.
1) Knowing when to fight is key. Fighting when you have the same amount of units as your opponent while you have a unit shipment and a batch on the way surely isn't a good thing. Even with a poor micro, you'll do much better if you know when to take the fight in order to get an advantage.
2) Knowing where to fight. Fighting in your opponent's base, in an open field, or between trees isn't the same at all, and engaging in all these situations (and knowing how to retreat if needed) isn't something you're going to learn in Time To Micro
3) In a real game, you do not have the same unit composition as your opponent. It just never happens, unless it's 100% musk vs 100% musk. So instead of learning how to be 3 xbows up at the end of a bow/pike/cav vs bow/pike/cav battle (which is never going to happen by the way), you'd better learn in real games how to take a good engagement with skirm/cav vs skirm/goon, how to hit and run effectively with skirm/goon vs skirm/cav, and make sure you don't get caught how of position.
And most importantly, learn how to have a good unit composition which counters your opponent's. With a better unit composition, you can totally crush your opponent's army while ttm's goal is to teach you how to get a 2 xbow advantage in a specific situation.
"Everyone knows that blowing infantry to shreds with heavy cannons is the most satisfying way to win." Boneng