Question for those of you with motivated hard working children.

I was always a last minute crammer and it worked for me . At the end of the day it’s the end result that matters . No harm in suggesting revising before the last minute however if the test result is good then clearly your DC’s strategy , on this occasion at least , works . Have you looked at the volume of information that needs to be understood/ retained for Forces and would it really take 20mins alternate days for the next fortnight ?

12yo or 16yo DD might have been sane about it, still not quite what OP wants from her DS.
14yo DD would have obsessively revised (to point of damaging mental health).
DS1 would have done zero revision at all ages.
12yo DS2 would have done no revision, but now at 14yo, DS2 would do ok quality revision the night before, for up to an hour.

14yo DS2 has the healthiest & most sustainable attitude, imho.

2 or 3 half hour sessions during the week before.

At 12 for an end of topic test (what this sounds like) it would have been around an hour the night before, or possibly 2 shorter sessions on 2 nights just prior to the test. Remember they have literally just covered this in class so she hopefully has retained a lot of the information anyway.

What you are suggesting sounds very OTT - remember they will potentially end up with an end of topic test in every subject, so if they are doing 20 minutes per subject every other day ... well you can add up how much that comes to!

Generally DC's school assigns 1 or 2 lots of homework time to revise for a test which I think is about right.

You need to revise for long enough to get the best result you can,modified by how much you care about your grade,and balanced against everything else you need to do.
At 12 I'd be having a chat about how a bit more revision would probably have gained a better mark,about how it's good to practice revising as you'll need it more and more,and about how to do it - some children have no idea how to revise.Not all in one "ok,DD,let's talk about revision" session though,just in dribs and drabs

Your plan is too much for that kind of test,and the night before isn't enough IMO.(unless revising the night before gets you 90%)

Mine (now 17) would have revised a single topic test the weekend before. Maybe for an hour each on Saturday and Sunday, and then the night before.

I've got 2 very different DCs.
DS (12) recently had a science test on forces. He spent precisely 10 minutes the day before, flicking through his book and got 78%.
DD (15) has to spend hours on that sort of revision ( she has poor short term memory) and would be thrilled if she got 60%; the last physics test she took, she got 35% ( forces and waves).

Horses for courses, I guess. I'm hoping DS will step it up once he finds a reason to. DD, on the other hand, will never get results that reflect her effort, so shell have to find a balance she's happy with.

I don't think there is enough in 'forces' to revise it for 20 mins every other day for 2 weeks.

otoh leaving it until the night before isn't good either.

At age 12 you could let her sit the test and get the 60% and explain to her that had she revised properly she'd have got a higher mark. You know your kid and what will motivate her. My DS would be upset to get 60% in a test so he ensures he knows the topics beforehand, hence the revision the night before.

To be honest, I never revised and did very well at school but I retained information well when I was a young 'un. Now I have a mind like a sieve ... oh to be young again!

Does she get good results? If so, that obviously works for her. I was the same and got top marks in most things (back in the days when my brain functioned!) 😆

My DS is 14 and in Year 10. He is very motivated to do well academically because his dream is to study a course at Uni that requires AAA at A level. It's seriously competitive to get in so no chance of the Uni accepting lower grades. He's currently predicted 8/9 in all his GCSEs, purely down to his motivation to have an excellent application to this course.
My DS would only have ever revised for a test like you describe the night before when he was 12. He does has phenomenal recall and finds Physics really interesting. That, combined with his motivation, means that he's excelled in his class tests with only revising the night before.
He is aware he'll need to do in-depth revision for the actual GCSE exams but hasn't needed that for any of his class tests so far.
Hope that helps!