Thanks Satan!
On the PIK one we waited till 1m15 (so rolled at the standard time) about 1:45 airborne after the heavy (not the best I admit!). Hence my question, do you adjust for destination? 45s does seem to work for most of our routes though.
There is of course a flip side to this, the takeoff time for our longer range destinations could of course go a little the other way...A 321 with destination timbuktoo takes a longer time so you could think about issuing the clearance slightly earlier (tin moving etc!).
As for hanging around routinely - Nahh, no way! And winding up when things are tight - some of us do that anyway (particularly prior to 7am...)