It doesn't matter if you have sprints of kanban, if there is a deadline is project managers need to do the same work to verify things are progressing fast enough for the release. This work is estimating how much time remains, and if there isn't plenty take action. The plenty part is where most management goes wrong: they want everything done on time, but the only way to get that is have everything done early. That in turns means you need to have at least 20% (the higher the better) of the things planned for your deadline things that you are willing do allow to slip to the next release. Of course working against that is the human tendency to polish things until the last minute, but that shouldn't be managed by the deadline (even though it often is)
I'm against the web release early and often model - don't make your users your beta testers. I'm in favor of spending several months of test after the branch to ensure everything is stable even though this is a lot more expensive. I do agree with the web have automated tests for everything model, I just don't think automated tests alone are enough quality control - automated tests ensure that everything you can think of didn't go wrong, manual testing is about noticing things you didn't think of. (you will note I work in an area where my code can kill people)
