Well, a bit of specificity seems to be paying off for me. Managed a 15s hang on the 6mm today which is 200% better than any previous effort! This with totally fresh finger pads - next go felt vastly harder and I reverted back to the 8mm for the rest of the session - but very encouraging.
I've also been very consequential with the antihydral the last week and have carefully sanded the skin smooth etc which presumably doesn't do any harm. Now actually really psyched to see how far I can go with it, although I don't think I'll be approaching the 16 pull ups mark any time soon