It often gets overlooked that, as well as all the academic learning in school, there is a massive amount of independent learning and independent thinking being taught.
Children need to start taking responsibility for themselves right from the start in Reception. Simple things, like looking after their own belongings - your coat goes on your peg, your gloves in your pockets, your lunchbox on the shelf, etc. So many parents do not allow their young children to do these simple things for themselves.
There are children in Year 2 who cannot do up their own zips on their coats or tie their shoelaces. They don't bring the right equipment to school because 'my mum forgot' when it is their responsibility to organise themselves.
These are very simple life skills and many children are lacking because they are not allowed, by their parents, to take responsibility for themselves.
Being trained to drink at convenient times is also a life skill. Learning that the beginning of a lesson, or during an assembly or a PE lesson is not the best time to leave for a drink or to use the toilet, is all part of the learning that happens in school.
That is why there are set times to drink and use the toilet. Before school starts, during morning break, at lunchtime and after school. They are told and reminded and, if desperate or if they have medical conditions, allowances are made. But on the whole this is just one more life skill that children need to learn.
Drink when the opportunity presents itself. Think ahead, you might be thirsty later if you don't drink at regular intervals. Think for yourself, keep yourself healthy.