I get what you mean but I think it is also supposed to teach you to notice patterns faster.
Tactics Trainer timing

I think the time thing is only relevant if you play a lot of speed games. It messes me up; I feel too much pressure and you don't get a second chance if you get it wrong first time. That's why my rating on Chess Mentor is almost twice what it is on tactics trainer!

I think the time thing is only relevant if you play a lot of speed games. It messes me up; I feel too much pressure and you don't get a second chance if you get it wrong first time. That's why my rating on Chess Mentor is almost twice what it is on tactics trainer!
Analysing lines and spotting tactics quickly isn't only useful in speed games, it helps you see a lot more, reject certain candidate moves and gives you more time to evaluate features of a position, come up with a plan etc. Knowing the basic tactics well also makes you look at key features of a position and consider moves you may otherwise reject.
I don't think the timer is bad, it's just a different way of practicing tactics, focus more on pattern recognition than brute calculation and accuracy. You can use books if that's how you want to study tactics, a mix can't be harmful.
Your rating on chess mentor has more to do with chess mentor ratings being random than anything else, and the points system being completely arbitrary.
Is it possible to turn the timing option on the Tactics Trainer off? While the timer is a great way to train there is something to be said for taking your time through a tough set of problems.