I try to do my checks quickly - but have noticed that when a bit out of practice I can miss items - so I slow down.
Usually I can do my checks without holding anyone else up, but saftey first if I need the time I take it.
It is quite common at my local field for someone to take off from the intersection if they can fit in, I've never seen someone give offence that I know of.
Also it is not uncommon for people to call out "back tracking for departure in turn" and 3 or 4 aircraft can expidite departure by backtracking together. The following aircraft just taxi onto the peri track at the end of the runway. I've seen twin turbo probs fitting in with microlights doing this.
Everyone calls what they are doing.
I use the full runway even in a quite high performance plane capable of using less than a quater of the runway. Its my choice, I don't think people who depart from the intersection are taking an unreasonable risk.
Finally I hope this isn't a thread highjack, it's all meant to be about expaditing departure.