Just a suggestion and my subjective view.
I suppose that every game I play will end up in around 50~70 moves, so I roughly calculate how much time I have for each move with the time.
Of course, in the beginning, it is almost always the same basic opening and follow ups, so you can spend more spare time later on for tactic development and strategies.
I am seen that not giving enough time has become rather habitual. It seems i get 'annoyed' if i do give a lot of time to a move. What seems perplexing is that when do you calculate and how much should you do so? (something which players may know instincitively but i don't have this instinct). And i seem to find better moves when i give more time but how do i make myself commit when calculation is needed rather than playing fast pace throughout the whole game?