I think as tempting as this may be the question has to be how much is enough?
If you can/have already comfortably retired early in your 50s do you really want to go back just for 'that bit more' . Unless you are in a rewarding field that you genuinely enjoy (not just tolerate) I fail to see the point of coming back, especially if you can already afford to do all the things you would ever want to do.
You can't buy time, always makes me think when you ask the 85 year old billionaire if they would forgoe their fortune to be 21 again.. Im sure there would be a fair few takers!
A bit off topic, but as a case study... I'm in my early 50s and have "enough" to retire and am still working for "that bit more". And it's complex.
If both my wife and I were to retire then even with the amount we're saving we would still have to cut back on spending either if we were on the dividend income or if we were wihdrawing 4%. It would still be comfortable, but it would be a noticeably cut back. Fewer coffees, holidays, trips to the pub, presents to family, donations to charity. We've cut back on these already (not the donations to charity - but that's accident, not virtue) in the past two years, but it would still be a clear cut.
We could withdraw more and spend about as much as we do, waiting for her public sector pension and later our pensions to set us on an even keel. And although I've calculated the burn and we
should be OK, it's still a risk and the calculations were close.
If one of us were to retire then that bit would be OK. Much less would be saved but we'd comfortably be able to maintain our spending. The question would be who would retire. I may be older and it may be my money that we can access now, but my wife is the one with the migraines and a desire to be an artist whereas I would probably read all day and edit Wikipedia - so we've not had that discussion.
Part time work would be an option, but for me that would probably be an end to home working and for her a bit of a drop in status that she's not ready for.
So we earn that bit more and wait for that point, which should come up reasonably soon, where the income from our investments equals our spending and the choice becomes and bit easier and the excuses become harder to concoct. That's the "little bit more" we're going for.