for me it depends on who I'm riding with

last week I did 125-130km ride

we started with 5 minute pulls in a group of 3 and on the way back it was obvious people were suffering so I pulled longer.

we probably could have had shorter pulls but when you have a small group I find it easier to have a rhythm with longer pulls

if in a group of 10 the pulls are much shorter and if the average speed is faster.

one tip though is pull off when you want to even if your "time" is up..... for example if you are the wekest climber finish the climb and pull off, don't pull off before/during the climb if your not comfortable you can grab the last persons wheel because you are fading. THat being said if you are pullnig through and know the person pulling off is a weaker climber don't be a jackhole and up the pace.