Its not that i dont calculate when the situation requires, but in tournament poker there isnt many instances im gonna be calling to hit a hand so pot odds dont really come into the equation. Draws are death in no limit becase if you miss on the turn you probably will have wasted those chips because it will now become too expensive to see the river. If I pick up a draw and sense my opponent is weak im a lot more likey to move in, cos if you are correct he will fold or may fold top pair marginal kicker etc... or if you do get called you ge to see both cards to try and make your draw. If you feel your oppenent is strong just fold the draw its not worth it.
For the reasons Pab states, calculating the odds on the flop (outs x 4) can get expensive when you miss on the turn.
You have to remember that you only get 4% / out if you see BOTH the turn & river cards... so if deciding whether to get into an 'All-In' situation then it is a useful calculation.
If just deciding whether to call a bet , then I think it is best to treat the odds on the turn and the river seperately... ie. 2% / out to hit ON the turn and then 2% / out to hit ON the river.
If you have 9 outs on the turn (appx 20% or 4/1) AND you are fairly sure you are drawing to the nuts and calling a bet on the turn offers favourable pot odds ie. >4/1, then for me it's a call.
If the turn misses, then it is the same calculation... if the other player/s make the 'mistake' of allowing me better than 4/1 pot odds to see the river then I'll usually see it.