This document from Estyn and co-authored by the various Welsh Local Authorities Education Services. bit.ly/38axmot
The document says "The requirements of social distancing point to bubbles with a single class base and staff moving." and "Learners could come in for two half rather than full days".
The 2m social distancing determines that. Teachers have told me that is why they can only do 1-day-a-week at the moment. Unless they scrap social distancing.
Unfortunately that looks unlikely, as the First Minister on Friday stated blended learning would happen in September:
"" ... we will still have Coronavirus in circulation in Wales in September, unless things go far better than anybody is currently predicting.
So there will be some aspects of blended learning, learning in school and learning at home, at the start of the new school term."
You can see the full Q&A with the First Minister at this link www.pscp.tv/w/1nAKEAlbnEXKL
Education section starts at 17min:25s