If you start from a raw file, re-editing and saving as jpg produces no further degradation.

If you start from a jpg and edit that, you will get some degradation but if you write it using low compression the degradation is small.

If you always start from the original jpg and edit that, you can keep further degradation minimal. If you use a parametric editor you can start from where you last stopped without any further degradation.

But always 8 bit