If I were a doctor, I would say that what I am about to tell you is correct because of my immense medical knowledge. But I'm not a doctor. What I am about to say is correct because I've tried it for myself and it works. (For me, but I think it will work for you too.)
Oddly enough, my inspiration for this article came from watching the UK's Chancellor of the Exchequer read his budget speech to Parliament a while ago. As he worked his way through the speech, his voice got hoarser and hoarser. And although the House of Commons has a voice reinforcement system, he was struggling against a considerable background of murmuring and shuffling from the jam-packed house.
The reason for this hoarseness is, in all probability, that he doesn't normally give such long speeches, and not in such a noisy atmosphere. Speaking up, even if not speaking loud, for a long period started to wear at his vocal cords and surrounding throat tissue.
And it's with same with singing. If your band performs once every other weekend, then that's the only time your singing muscles are really used to the full. And that's why you end the gig with a sore throat. Singing the odd song in between, or even rehearsing where there is (or should be) many intervals for band discussion, doesn't impose the same kind of stress.
I would liken this to a guitarist's fingertips. When you first start playing a steel-strung guitar, it is painful. But as you practise and practise (hey, in the UK we like to spell practise as a verb when it's a verb) your fingertips respond by toughening up.
And that's what your throat will do, if you sing regularly. If you make it your daily habit to sing for half an hour, (come on - half an hour against undoubted fame and fortune?) your voice will be robust and sore throats will become a thing of the past.
I don't think it's a good idea to try and force things so don't sing until your voice is ripped to shreds. Sing until you can feel that your voice has had a work out. Recover overnight, then sing again.
I may not be one of the best singers in the world. In fact I may just be one of the worst. But I know that if I get out of practice (noun), then I can expect some hoarseness next time I sing. If I sing every day, my voice becomes robust and there's no problem. And actually, it sounds better too!Come on the FREE COURSE TOUR