I'm fine with soccer, boxing, cycling and swimming being my main 4 out of gym activities for next year. That and the occasional hike

Probably anatomy based to some degree. If you are top heavy with bad form snapping your shyt up can happen.I've never been in the agreement that sit-ups are bad for you or give limited results. I find them to be very effective.
I've never had back issues with them, and I see fast results from them. The only knock is that they don't target your lower ab area as much. I can live with that and do other exercises for that.
It’s important to take extended rest especially if you’re really active.Starting to understand why some people don't like taking a week off...
I schedule 3 1-2 week breaks a year. Is this not enough? I do feel a plateau.It’s important to take extended rest especially if you’re really active.
A lot of times people plateau or overtrain because they don’t rest enough.
I take certain things like rain or any time of doms as a sign to rest a bit more. I usually come back with an edge, indicating that my body needed more rest.
There are way too many unknowns for anyone to give you a good answer. How long have you been lifting? How often do you lift? What does your routine look like? Are you seeing progress on your other lifts? What are you doing on none lifting days? There are so many factors that can impact your progress. Why do you take 3 1-2 breaks a year?I schedule 3 1-2 week breaks a year. Is this not enough? I do feel a plateau.
Rain?