That's my personal opinion based on the development of numbers in different countries. Luckily Switzerland didn't have any major superspreading events in schools so far. Might be different with new mutations, but if it is that different the masks won't help anyway. 20+ kids staying in the classroom (my daughter's classroom has ridiculously low ceiling, so the volume of the air inside is really small) even with airing during breaks creates good condition for spreading, masks or no masks. Some kids will probably wear same masks for a few days in a row, noone will wash hand after taking them off and eats their Znuni with these hands, still communicate without masks after school, visit each other at home etc. I know that they are still sharing food even though it's prohibited. Kids are kids, you know.

Please provide evidence for your words "too late". Has anything critical happen in primary schools during the epidemic that influenced the situation in Switzerland significantly?