I've been intrigued for a long time about "waiting for the last person". Climbing Mt Gower on Lord Howe Is sealed it for me. Climbing group were varied in ability (but not intent). Fast, fit people would forge ahead with guide; second (self seeded) group would tend to fall behind. First (fitter) group would end up with longer rest time (and viewing time) as climb wore on.
Simon was heard to say that a longer rest time as your team mates get more exhausted means you can run harder on later intervals - and he was certainly observed putting this into practice!