Our local secondary school (which I work in as well as being the school DS goes to) allows masks in class if kids/staff feel happier with them. But teachers can't teach in a mask - the kids can't hear so they have to come closer.
The kids don't wear masks as we have enough space to do one way systems etc., but that means any child with a cold is sitting next to all the others. At lunch time they all congregate around the canteen tables. The best our lunch staff can do is ensure the tables are wiped down after each group has left and do a big wipe down as the year bubble leaves, to stop the spread across bubbles.
All the kids walk or bus in together. They wear masks on the buses but, of course, they've not necessarily got them on for the time they wait for the bus. As they meet friends, that could be a 15 minute natter before the bus arrives with no-one checking they're socially distancing. On the way home they are kept in sensible lines with masks on but that's because the bus is waiting in its queue for pick up. Our teachers do watch over the kids who get the general buses and encourage them to put masks on in the queue outside the school. After that ... who knows?
Those who walk certainly don't use masks most of the time.
I help out in an SEN class first thing in the morning to allow teachers to get to classes - they're obviously moving rather than the kids so all staff are on 'class watch' duties where possible. We can wear masks but we have a few children in the SEN class that really find masks hard to cope with, so most of us use a visor or nothing - the kids come first and we're not going to cause them distress for the day. The problem is that a few of these kids are huggers or have no concept of space - which isn't a problem in normal times but with Covid around? So you're constantly reminding them to step back from each other (or you) or doing a social distancing 'waltz' with them coming towards you and you backing away!
There is no social distancing in schools - I can't understand how anyone who has a child at school would imagine there is. The best they can do is sanitise, clean and keep bubbles apart. Kids aren't robots so the best you can do is keep reminding them - but of course, that only happens after they've hugged someone or jumped on their mates or started to fight. You can't anticipate a child's mind or movements.