I found that "screens after N pm" worked well for us. It created a zone where there was no consideration, expectation, or backsliding onto screens. We also kept a VERY consistent bedtime, so that "N pm" to just before bedtime rituals timeblocked screens.
If you get on a screen at 4pm it can be hard to suggest putting the screen down to go outside or do something else.
Was that a "no screens after N pm" or a "screens only between N pm and bedtime" rule?
I can imagine the latter working well, but we never tried because we're worried about screen exposure close to bed time causing sleep issues (blue light, but also because content on screens seems to excite and energize kids somewhat) - we're already having way too much problem getting kids to sleep on a sensible schedule.
The latter -- and getting to sleep on a regular schedule wasn't really a challenge in my situation. We did consistently start it at a certain hour, though.. so it would be, say, 7pm to 830pm and then start the bedtime rituals.
Would you change your rules if your kids showed interest in developing actual computer skills? My parents had rules similar to yours and wouldn't budge, and it effectively killed a decade of potential programming experience. I still resent them for it to a point, but I realize they were just ignorant and thought learning to program was equivalent to playing, because I was at the age they thought I was supposed to be playing.
Just... try to avoid making your kids be something they're not, in general.
If you get on a screen at 4pm it can be hard to suggest putting the screen down to go outside or do something else.