One of the best things about thermovite is it is quick and easy to give the lamb a squirt. Then if you are too busy to mix colostrum or have to attend to something else, the lamb you gave the thermovite to will be OK for a while, until you DO have the chance to go and sort something out.
I don't like stomach tubing - I can do it, but I prefer to leave it to Tim, so if something is born on my shift that needs tubing, I can give it some Thermovite and be content that it will be OK until Tim is about. All triplets are given thermovite as routine and also anything that is weak, slow to get up or suckle or if the ewe is flighty and won't let the lamb feed.
If you have got pedigree sheep (which are worth more) you can probably justify giving a dose to every lamb born.
It works for calves too.