I see it through both ends of the telescope. Not only do I work to a very tight programmed schedule of servicing and/or breakdowns..but we regularly get extra jobs 'dropped' on us, so we can easily end up with 10 jobs in a working day, but we have very tight appointment keeping rules, and my travel is not usually far. On my last callout saturday I did 14 breakdown jobs. Its not always like that, but it can get pretty hairy, and we don't have a 'finish' time as such. Under our contract our day is only finished when all breakdowns phoned in by 3 pm are done...callout engineer gets any that come in later.
I also have a cottage Oop North which is under a BG Three Star contract after the local Corgis let me down too much. The service I have had has not been bad at all, except when they sent me a letter this summer wanting to inspect the meter, and threatening forced entry if they were unable to get access...then they failed to turn up!!! I hit the phone and gave them absolute hell, and they got an engineer out first thing next morning..the louder you shout etc etc. He explained some of the problems they have.
The engineers I have met have all been very competent and dedicated, and like me, they get 40-50min or so to do a service/fix a fault..which is often not enough. I can call on local backup though if I hit a snag, they cannot. They also said there is a shortage of young engineers, and a lot getting close to retirement, so I think the service is probably oversold, and they can't get the staff to fulfill the contractual obligations.
Alfredo