I shoot rifle rimfire without protection sometimes, especially at steel targets at longer ranges because the sound of the hit is sometimes the only way to know you made the hit. As for any handgun, rimfire or centerfire, always headphones, same thing with centerfire rifle. In the past I've fired pistol caliber carbines without protection, you can get away with that sometimes, other times you can tell it made an effect. Shotguns, always protection.
Its an interesting debate, should we do more training without protection because that's what real life shooting will be like, and we should be as realistic as possible? Then again we know that too much shooting like that isn't good for you, its a debate with valid points on each side. I don't use eye protection, because I feel that's something I can "get away with" and remains more realistic for hunting and otherwise when you don't have glasses on. Like everything in life, we calculate the risks and make our way forward.
As for shooting more rounds less often, I somewhat agree with that notion. Some days there's nothing better than sitting down and shooting many rounds and calling shots, learning from mistakes, getting better, finding your weaknesses and shooting till you correct them. Real validity to this method. On the other hand, I am trying the shoot every day method because of private property so I can do it whenever I want, also once you do become proficient as a shooter its a decent way to keeping up proficiency. Also, cheap fuckers like me try to save every penny, next thing you know I'll sit on my cache of ammunition waiting for a "big shooting day" week or bi weekly, next thing you know between work fatigue and putting it off I might not shoot for months. Having a rigid daily schedule, so many rounds with each rifle each day, makes you stay on track and keeps you shooting all the time. Before you know it, shooting Saturday or Sunday gets lost because of events, friends, weddings, family events, ect., and you lose track. 15-20 rounds a day is short and easy enough to fit in.
In either case, we can all agree that 20 rounds is fucking nothing. Wither I shoot 300 rounds a week with daily shooting plus extra, or you shoot 300 rounds once a week at the range, or 600 rounds a fortnight, 20 rounds per month is fucking crazy.