Really recently I started to actually write down my ID process when I spend a bit of time trying to identify something new. It’s time consuming for sure, but I find it’s really helpful both for other people and for myself in the future when I’ve forgotten everything that I learnt. Previously I would spend ages on an ID and then not write much (or anything) down about how I got there, which I reckon is just a waste of time! That way after I get a name I can link back to it when I ID it for other people. (I’ve also collected them all together here)
In terms of identifying other people’s sightings, I agree that it’s often a toss up between adding comments or making lots of IDs. If someone asks me how I IDed something, I’m always more than happy to explain my reasoning. If I’m just going through making hundreds of IDs though, I tend to avoid comments unless it’s something unusual or someone has tagged me specifically