Re: Andrew Moore
"If management have the option of keeping someone who's competent enough to do their job within their contracted hours, or someone who is either slow and/or incompetent enough that they need way more time to get the job done "
You missed the possible paradox "[...] they need way more time to get the job done" ...properly.
I often had to pick up the pieces for people who had a strict 9-5 routine that left loose ends dangling when they went home - and that they failed to pick up cleanly the next morning.
For some problems you have to stick with the task until you reach a safe breakpoint. That can either mean an early finish or a late one.