time management

While playing the fried liver against an opponent the other day, he complained that during a 15 10 standard game the time wasn't long enough. The time is perfectly fine to me, especially with a 10 sec bonus. The thing that really grasped my attention however was that he only thought when his turn came up. The rule in chess is that you can't move until your opponent has, not you can't think about your next move until your opponent has. Has anybody else run into this type of player?  

If it is not long enough why would he play the game .

I said the same thing Equiv. 

Yeh, I can relate to that. Or there are players who will choose 15I10 and then will always run out of time. I'm not sure though they don't think while waiting for opponents move.