So many of these are standard if you were born in the 60's/ early 70's. Based on both costs and commonly held beliefs.
Phone calls were expensive. Not many people had a home phone so there was nobody to ring really. And once they became widespread the phone bill was monitored like crazy to make sure money wasn't wasted. If we went somewhere you would ring home, let it ring 3 times and hang up. Heaven forbid someone answered before the 3 rings. As that would cost money.
Immersion heaters (if you had one) were expensive to use and refill hence limited baths. We had a shower attachment over the taps or people had flannel washes on non- bath days.
Water shortages was a thing early seventies so the not bathing everyday kind of makes sense. Plus shared bath water (tin bath) in the 50s and 60s probably explains the no baths on a period thing. Especially before central heating / showers became common.
Being ill and staying in bed was to discourage skiving but also to try to stop any illness from spreading to the rest of the family. A necessity in previous years when people would die from childhood Illnesses. Likewise. No nightwear outside the bedroom was to try and stop you catching a chill.
I had a pretty chilled out childhood but things like parents controlling the tv, no dessert during the week and only if we had eaten all our dinner etc were pretty standard.
Pillowcases for Father Christmas presents was one that brought back lovely memories. Our wrapped gifts were downstairs but we had to wait before getting up. Makes sense as allows the parents a lie-in.
Then there were all the polite manners ones like not eating in the street, not referring to people by first name etc. I. A working class area it was seen as common and nobody wanted to be common. Lol.
Some of these are bonkers but a lot are just nostalgia and In the context of the cost of living actually kind of make sense. 