We had to do the walk twice on some weekdays as well since we always went back to the houses for lunch and twice a week had to go back for lessons again in the afternoons.
On the other afternoons we had hockey in the autumn term, lacrosse in the spring, and cricket, tennis and swimming in the summer. On the days we had lessons, we had a reduced amount of prep.
Good grief - ten years later, and at a different school, we had to walk back and forth from the boarding-houses (cycle, when we were in the senior houses, from what is now Year 9 upwards) four times a day, as we went back to the house for lunch. If it was wet, they would lay on coaches, which was rather nice as it was less rushed. When I was in about Year 10, I think, new kitchens were built and new dining-rooms, and after that we had lunch at school, and supper was sent down to the houses from the central kitchen, rather than cooked in-house, as it were, with predictable impact on the quality of the food. They could produce decent food when parents were around, but most of the time... not so much!
We had lessons every afternoon, although ghastly lacrosse happened at least three times a week, known as "Fields". But one might have, for instance, Latin or German in the afternoon as well. We didn't have lessons on Saturday mornings, just hours of prep (I think it may have been 2 hours, as opposed to the 90 minutes that were the norm on weekdays, often interrupted by one's bath).