Yes, Katalon seems to be waiting for page loaded somehow. But, as far as I know, it has not been well documented how Katalon behaves for “wait for page loaded”. And I do not know it either. I guess, the implementation of “Default wait for page load” is so complicated that Katalon Team is reluctant to write any description about it.
When I am serious, I personally do not rely on Katalon built-in features so much for making sure page is loaded, because I can not be confident of. Rather I always prefer “WebUI.verifyElementPresent(a specific HTML node, timeout)”. I always choose HTML nodes that I expect to be loaded lately. I am always specific which HTML node in the page to look at and how long I am prepared to wait for the node to appear.
See also this say:
If you are working on a serious test and want to be 100% sure, then quote from this say:
So, there is no one-shot command/API to solve this – the solution is in the (your) approach.
However often I play on easier tests, then I would relax; I too rely on the “Default wait for page load”, leave it as is, and would not mind how it works.