I can think of a few instances when it hasnt really worked like that, Telic one had to have 1GS and 2CS merge in 2 LSR. Herrick 6, 4LSR had to ask for extra suppliers (From 6 regt I think), Telic 11, 12 LSR had drivers and a chef doing supplier work and then 6 regt had to provide more.
I always thought having seperate transport and supply regiments is a better idea (more SMEs and better trade orientated exercises). Then when a tour comes up choses seperate sqns from each to deploy. The main problem being who is the CO in theatre.
And DE gaps if APC continue ******* people around and posting them to god-knows-where at short notice (then telling everyone "needs of the service come first and if you don't like it, there's the door" while conveniently forgetting the second part of the principle!).