I first went to school in the mid to late 70s. I know that back then int he second year of school you were expected to sit and do school work for most of the time. We did have a lay corner - I remember the little wooden house with a cooker and a little bed - but that as for when you finished.
My sister went to school in the mid tolate 80s. Again, quite a lot of sitting working was expected.
I work in a y1 class. there is very little sitting still required in comparison.
Today's example:
8:40am - doors open; activities out to do and choose from such as role play, water and sand, colouring, books, jigsaws, computer, car mt, bricks, etc.
8:50am - sit on carpet for register and dinner list; a few minutes sharing
9:00am - choosing time or "continuous provision"; within this time teacher and TA called children in groups to come and read - meaning 5-10 mins sitting down
10:00am - phonics sesson; sat on carpet working in pairs and at board, using own white boards, etc. Involved standing up activity and singing
10:15am - snack circle and story time; sitting down on carpet
10:30am - play time
10:45am - assembly
11:05am - carpet time for literacy
11:20am two groups at tabes to do wiritten work; thers doing continous provision
11:40am - groups swap over
12:00pm - lunch time
Afternoon involves more practical activities generally such as PE, dance, craft, cooking, science, etc.
Often in a morning we will also have additional outdoor time.
We sometimes do some numeract as well as literacy, if there is no assembly.
I don't think there is too much sitting down and listening time TBH.