Is this normal? Or am I putting the glue on too thickly? I only ask because I have read that people say they are quicker to replace a tub than a clincher.
It can be quicker but it does take some experience. Basically you need to have an eye for where the weakest spots can be: spoke hole areas are your most obvious targets.
Keep in mind also that some of us build in some weak spot just for the purpose of being quick in changing a tub.
It usually involves an easy to remember spot, right opposite the valve, at a spoke hole for instance, that receives no cement on the the tub's base tape. Just an example.
It doesn't need to be be more than say half an inch, just enough so you can worm a plastic tyre lever between the rim and the tub to get started.
Don't worry, it's perfectly safe. It takes a lot of odd forces to actually roll a tub.
Thick layers of cement are actually even easier but unwanted as they take like for ever to fully cure and up rolling resistance since they just stay too soft. Too much room for minuscule movements creating losses.
Being a snob is an expensive hobby.