Ten months notice - Wow, that is WAY too much. If anything that's a strong indication that you or your company failed completely at your duties _prior_ to your resignation. A "professional" would never let themselves or their company be in such a position of utter dependence in the first place. Two weeks notice should always be sufficient for both parties.
FWIW I gave 5 weeks notice at a job a decade ago and immediately regretted it - the last few weeks were beyond awkward as I'd already wrapped up all my projects, spoken to all my colleagues and clients, etc. I was waiting for the job to end but kept getting roped into last minute projects that I could not in good faith contribute to because I was, admittedly, just sitting around waiting for it to be over. Everyone lost.
2 weeks max is optimal and expected for everyone. If you're feeling pressured to give more time to the company after resigning, say no and stick firm to 2 weeks. If they've got actionable work and you're able (i.e. not exclusively employed immediately thereafter), give them the option to hire you as a contractor. If the work is actually valuable, they should have no problem cutting you a check to complete it as a consultant. If not, well they're lying to you and stringing you along to extract any value they can - and you should leave in two weeks if not sooner.
I gave that much of a heads-up of my leaving (not a formal resignation, as it happens) for a few reasons including:
1. It's a C-level replacement, which takes _months_
2. I cared deeply (and still do) about my team and the company mission, and wanted them to succeed: "the more notice the better" seemed right to me (it wasn't)
3. My career plans were to move into a new field which would require various courses, lots of reading, conferences, etc. – although I knew I was leaving, I hadn't even started speaking to potential next employers or investors when I told my CEO I was leaving
Putting all of that together is how I ended up with the 10 month blunder, but the post is less against 10 month notice periods, and more for matching the notice period to your handover, whatever that would be.
I feel your pain on working out those 5 weeks you mention! Awkward for everyone involved.
FWIW I gave 5 weeks notice at a job a decade ago and immediately regretted it - the last few weeks were beyond awkward as I'd already wrapped up all my projects, spoken to all my colleagues and clients, etc. I was waiting for the job to end but kept getting roped into last minute projects that I could not in good faith contribute to because I was, admittedly, just sitting around waiting for it to be over. Everyone lost.
2 weeks max is optimal and expected for everyone. If you're feeling pressured to give more time to the company after resigning, say no and stick firm to 2 weeks. If they've got actionable work and you're able (i.e. not exclusively employed immediately thereafter), give them the option to hire you as a contractor. If the work is actually valuable, they should have no problem cutting you a check to complete it as a consultant. If not, well they're lying to you and stringing you along to extract any value they can - and you should leave in two weeks if not sooner.