Now then Wombat ..... you're applying common-sense, and that won't do !!!
Nope, we pick up 'Cab only' self-installs at random times. I've been at one Cab when two other engineers have turned up to do the same work on 2 other separate circuits.
To be fair to OR, they are very simple 20 min tasks, and they like to use them as 'infill work' if all the appointments have gone out, or at the end of the day.