There are 3 recall sessions for each show on each weekend day - morning, early pm and late pm. The exception to that might be the showcase concert, as not so many have specific recalls for that, but bear in mind many people recalled for a show might well not get cast in that show but in the showcase instead. There are usually about 15ish people in each recall session, so possibly up to 90 or 100 will be seen for a show that can take 30. BUT, some of those will have double recalls and obviously can't do both, some of those will get showcase (which might be a bigger cast?), some will get workshop and some unfortunately won't be lucky this time. Basically, if you've made it to recalls you've done very well, but nothing's guaranteed. If I had to hazard a guess I would say teh recallees have about a 1 in 2 chance of coming away with something, but it might not be one of the 3 summer shows and could be showcase or workshop. Both of which are great experiences and really worth doing so shouldn't be seen as a consolation prize. The workshop creatives are sometimes at the recalls too (no idea if they will be this year) so they get a say too sometimes.
In terms of results, historically they tended to come out towards the end of the week following the recalls. The pandemic really kiboshed that for various reasons, but this year we seem to be back to hearing fairly swiftly after first rounds, so I would like to hope that the casting results won't be too long following on from the weekend.
The recalls are nice because they are all different ages jumbled up, so it's not at all like they are viewing 15 little girls and only 1 can be Matilda, for example. People may read for different roles or end up cast in a role they didn't read at recall. They won't explicitly say if someone is being considered for a specific role, but a lot of careful discussion goes into recalling people, and I'd be very surprised if they don't have a few strong possibilities to explore at the weekend already.
Hope that helps!