It depends on the school mrshamlet
I wouldn’t work somewhere with nonsense like the seven part lesson.
Children are quite capable of understanding that things can and do differ between lessons.
Some teachers will feel unsafe without masks.
Some teachers will feel that masks are detrimental to learning.
Neither are wrong which is why blanket masks/no masks approaches don’t necessarily work well.
giraffe I’m not making the rules here
I think it is reasonable for teachers to make their own minds up but personally I can’t say I’ve given it any thought beyond that. And if it is the rule that teachers decide for themselves then children bring a mask snd wear it when required and not if not required.
If your point is that they will forget their mask and if they don’t it will be mucky then I agree. Which is why it’s so hard to enforce in schools in the first place.