Firstly, people are generally terrible at estimating the effort/time required to complete a task, regardless of the domain it exists in. Secondly, I’d suggest that all the environments you’ve described are (in the main) decidedly toxic.
The over-riding impression I get is of you carrying the weight of lazy product development. As Peter Drucker quoted: — The greatest waste of time is doing something well that need not be done at all.
One thing we’ve done is spent more time making sure what’s being developed is worthwhile, rather than trying to deliver all the things. You can never do it all, so actually the smart approach is to do the 20% of the things that deliver 80% of the value. It’s never the other way around