So here's my take on it, guys.
If something has been inactive for 1-4 months, it's technically a smaller form of necroposting. We can let it slide but you're on thin ice IMO. Even more on thin ice if you post something NOT worthy to the discussion, but if it is worthy, then you're clear.
If something has been inactive for 4-12 months, then it's considered necroposting. If you show something worthy to the discussion, and the thread has not gone through it all and not done the "okay this thread can die now" vibe, then you're clear. If it does thave that vibe, or you're doing the same thing everyone else posted before, or it's not worthy, then you're a fucking idiot.
If something has been inactive for 1-2 years, it's definitely necroposting. If it is something to discuss, and it doesn't have the vibe of "this thread can die now", then MAYBE. But otherwise, it's better just to leave these threads alone because chances are whatever is in that thread is your answer.
If something has been inactive for 2+ years just fucking make a new thread if it so makes you curious.