Like everyone else said, it depends.

On long tempo rides it is nice to get into a rhythm of 4-5 minute pulls but sometimes if most of the group is exhausted one person may pull for 10-20 minutes or more. On faster (and shorter) club rides I will pull for 3-4 minutes max or if I'm barely hanging on I may rotate off right away; usually i am somewhere in the middle with 1-2 minutes on the front. I have had trouble hooking back onto the group, especially on aggressive club rides, but with some practice and maintaining awareness I can usually keep enough in reserve for that burst of effort.