I'm the odd one out, it seems. I bottle if they'll suck and tube only if I think they're likely to inhale it instead of swallow it or if they won't swallow at all.
I've never really understood this 'they won't go back on the ewe' thing. Since bottle-reared pet lambs all, without exception, readily transfer to a ewe if the opportunity arises!
Also, in my own view, with a newborn, if I can stimulate its natural suckling-and-swallowing behaviour, it's one step closer to getting on with suckling off mum.
A reasonably frequent scenario is that the lamb just isn't quite with the whole take-the-teat-and-suckle thing, but needs its colostrum. I'm very likely to milk some colostrum out of the ewe, bottle-feed it to the lamb and as soon as it seems to have the idea about sucking and swallowing, put it on mum's teat.
Tubing it gets it a known quantity of colostrum, for sure. But then it's happy warm lamb with full tummy and likely to go to sleep. So I still haven't seen it suckle and have to check back. And if it's midnight now and I'm about to go to bed, it could be a long time before it does get going on mum if it doesn't do it on its own.
So for me, it's horses for courses. I do use a tube if I think it best, but I certainly don't worry about using a bottle if the lamb will suck ok.