I gave 6 weeks on my last one to a fanng, Never again. That was when the project I was working on was slated to finish, and I continued working on it until then. I but it was a bit unexpected for me and I had a 4 day weekend scheduled to take my kids on a school trip.

Came back on Monday, incompetent fuckers had locked me out and terminated me as a no call no show. lol, uh, it's in the fucking time off tool you fucks. The thing that really sucked was that I was a high preforming employee, I canceled a promotion review to give notice. 7 years in and some jerkoff needs your seat and 6 weeks isn't appreciated. The got me reconnected after a couple days and then my manager never talked to me again. that was a long three weeks there at the end.

My experience is that two weeks is probably about right most of the time--especially for ICs. The company expects it as the norm. And it's either enough time to do a reasonable handoff or no sensible length of time is going to be enough. (And I'll always answer the odd "help!" question for the coming month or two.) Go much beyond that and you're in this odd extended winding down situation where you can't really take anything new on and you're increasingly checked out. And, in a physical office environment, you're probably also increasingly just a distraction.