I cannot cancel jobs quickly - in fact I often have the opposite problem - I try to cancel sleep so I can start the jobs I've queued up, and it doesn't always get recognized. And I don't always notice it until sometimes a half hour later, and now I've wasted a half hour thinking that my clicking on the X next to sleep actually DID something.
Every time I cancel a single job, the job queue rearranges itself, and I have to wait for it to refresh in order to kill the next job. Keeping my cursor over the bottom left job is not always the solution, because if I queued up some 15-second Grinding Coffee jobs for a daily, and failed to remember that I had already used 10 coffee I had left over from the other day, I need to cancel them before I waste that energy. And since doing all 4 15-second jobs 10 items each uses 80 energy, I do NOT have even 2 energy to spare, if I want to do anything besides logging off. So I need to kill the FIRST queued job, and then the next and the next, before the 15 seconds ticks down (and remember, it is ticking down as the job queue resets, so you don't have 15 seconds to kill any single job in that queue).
I'd much rather have that Cancel All Jobs button available - one click there and one more click to confirm, and I'm back where I wanted to be.
I understand the energy concern - you queue jobs before sleep and wake up with a full queue AND full energy - so if you cancel any of those jobs, that "saved" energy is lost. But if hitting the Cancel button provides a d'Oh moment, and you realize what you did but not in time to stop yourself, the confirmation popup should give you that second chance.
And the idea of it becoming a 'habit' the more you use it ... that argument would hold true for any aspect of the game, and I don't see it being used on a regular basis by anybody - it's intended to be much more of an emergency kill switch. For example, you see that dueler at your job site who's always hitting you and always seems to be able to beat you. You have several jobs queued and don't know how long that guy has been there, so you want to waste no time in killing each job in turn and then hiding in a hotel - you want speed, and yeah, even several seconds can help.