Both very true but also overrated, in a way. When it's cold enough to avoid overheat without sweating and the body is sufficiently used to the task at hand to not trigger much sweating proactively from exertion that's actually just barely enough to keep you warm you can get by with surprisingly little drinking. One rainy day on an 11h ride I only increased drinking frequency in the last hour or so when I realized that a bike with empty bottles would be easier to carry up the stairs.

quite true - i drank about a liter an hour throughout the trip and urinated pretty infrequently lol