The two trail repairs i've been at (Bills diff repair and my frame fix) seemd to happen at the ideal location. With bBikks, it was at the lunch stop on Wipeout. Repairs were well under way while lunch was going on and a few of us stayed to help while Time lead the group on off the trail.
In the case of my frame repair, we we just about off the trail. Tim, again lead the group off while a few stayed to lend a hand. Bill stayed because he had a wleder, Marco because he was good at Arc welding. A few others stayed just to help out.
I think knowing who has what or is good at what before starting the trail would make it easier when a situation does come up. That way a trail leader can delegate a small few while the rest stay focused on the trail....