I'm at the inevitable stage of a large project where planned work / remaining time > 1. So we ain't got more time. And we won't adjust the date. And we likely won't shed many features. Testing will suffer.
Maybe it's not that bad.
...and professional project managers cringe...
I've worked with a lot of smart folks with more formal project backgrounds (PMs, BAs, developers and QA testers). I've learned a ton from them. And I'm better for structuring my project process, particularly in the beginning months.
See, I'm more of a homegrown talent, steeped in the local corporate culture that is sometimes a bit too... cowboy... stick-and-rudder... for some. At some point, the wild west gets settled. The barnstormers get licensed by the FAA. And we continue our slow march toward respectable project execution.
I've also never forgotten that, at some point, a project has to see the light of day. Test all you want. Until code gets into the hands of the real end-user under production loads, you just don't know what it's going to do.
I don't want to sacrifice my test time. I really don't. Still, I have to acknowledge that there are worse things. My deadline might be tomorrow instead of a couple of months hence. So I do have the luxury of a little bit of time for some deadline freakout.
In the end, I think the lesson is that it's easy to postpone something as long as it never gets closer than a couple of months. Once the deadline is down to a few weeks, it's real. It's a go, or it's not. We're committed or not.
I haven't lost a project yet. I'm not gonna start now.