Earlier quoted context omitted.
These days I just immediately turn those down without a second thought. It's a joke of an interviewing system and your time is way too valuable for that. Happy to do coding questions, but not 8 hour long take-home projects. Those have screwed me too many times
Could those long coding projects be a strategy to force you into sinking so much effort into the process that you're now in a weak negotiating position due to the sunk cost? I admit I'm speaking from ignorance here, and am only curious to gain more insight into this.
Yes, absolutely they can! And almost nobody talks about this. Most of the conversation about take-home projects surrounds cost/benefit ratio, but almost never as a negotiating tactic and sunk costs.