A bit lighthearted but also a serious question!
Looking back at all the jobs I've had from age 16, working while at university and career after, it wasn't commonplace to have a Stanley or filled bottle nearby. We had breaks and mostly had a quick coffee and a food, same at lunchtime. No one took bottles of water, hot drinks or cans, that was it! At school also, juice at break and lunch then drink water at home.
A) On the one hand I feel the obsession with keeping hydrated has been propelled by the manufacturers of drinking vessels, especially with the imprinted quantities for times of the day, insulated to keep cool and so on. From this POV it seems OTT when people are walking around a supermarket with their bottles with the fear their bodies may shrivel up. In schools, having them on their desks, the bottle flipping, guzzling down a litre of juice from home in the first 10 mins of a lesson then desperate for the toilet, stating it's a human right to drink til you busrt! In addition the sales of plastic bottles of water to continue to carry around, you should see the bins overflowing with them in every classroom, so much for encouraging environmental values.
B) I've also realised yes it is important to keep hydrated during the day and we need more than a few cups of coffee as fluid to keep us sustained. I was one of the few, as a teacher, who would bring in a small carton of juice to sip at (days before reusable were used for anyrhing than to clip on your bike) as I got thirsty! I was however told off, that I shouldn't be drinking those few sips during lessons, yes truth. It was only a bit as drinking more would mean I would need to go to the loo, which I knew was impossible at break times when on duty or lunch when I had meetings, detentions, extra tuition. To walk to the staff toilets meant 2 blocks away outside, flights of stairs and a queue, so it was a scheduled comfort.
Back to the point...
AIBR Drinking during breaks and lunch is perfectly adequate, no need for constant sipping, especially in schools where it can cause so much disruption by those who take the mick.
AIBU We need to consistently sip to help us with talking, feeling well and focus.
As an adult I now value being able to have a bottle nearby at work, in the car on long journeys, but not a constant need everywhere I go. Xxx