On sipping versus drinking all of the amount planned for say an hour at the beginning of that hour (call it the batch method):
And with the caveat that I was not involved with any of the work and testing done with athletes along the way, this is only personal opinion.
Both release of fluid from the stomach and subsequent absorption in the GI tract are not all-of-it-at-once instantaneous processes.
Either way the time course delivery will be similar. There will be some extent to which the batch method delivers more earlier but I don't see where it can be a vast difference. If anything that is not a disadvantage for the batch method.
Where the sipping method has a clear superiority is in the context of athletics, which is what it was designed for and a large amount of the pre-release practical experience is in. Carrying around an extra 16 ounces or whatever of fluid and weight at any given moment is a disadvantage there. A "just in time" delivery system, so to speak, has an advantage in this regard in that context.
But lifting weights in the gym, that is not a factor.
So it really comes down to personal preference, I think, between those methods.