On an average session, I dive plus minus 7-15 meters, collecting muscles or spearfishing, and surface intervals probably average at about 1m 15 sec. This topic is really interesting, as it seems as though I need to give myself more recovery time. ( Only since using my D3 have I watched surface time.)
This may sound crazy, but if I had to ask myself what causes me to rush surface time a lot ...it' would probably often be on days that something has triggered my concience to be thinking of our Great White friends. They are far more like to hit you on the surface. A buddy of mine who has done a bit of research into their behaviour believes they will watch you for sometime, before deciding that you are not a 'scuba diver', but rather a seal ????
Nothing like these thoughts to get you scurrying back down into the deep blue !