revolution's thing works pretty well, as long as you aren't just dropping your hands after throwing them.
Too true. You need to throw from your guard and return straight back to your guard, almost as if there is a piece of bungee elastic linking your hands to your head.
Too many people throw punches which drop as they're thrown and then recover them by dropping them to waist-height and pulling them back up. The ultimate no-no. This often happens because they are having to use their shoulders to hold their hands and arms up. Once the punch extends out from the body that tension gets lost and the punch drops without people realising why.
If your hands want to drop because you're stood in the wrong posture then all the conscious drilling or use of tools won't help much - as soon as you remove the tool (be it a ball, tissue etc) then you have nothing to concentrate on and your body will revert back to path of least resistance.
Change the posture, change the effect - anything else will only happen when you concentrate on it. Which is fine when you're training but when you're under pressure or tired you can bet money on those bad habits coming back.
The underlying problem with hands dropping is all to do with what makes them difficult to hold up. Your hands only want to drop if that is the easiest thing for them to do. I refuse to believe that your anyone's hands want to leave their head open for damage (that only happens in Evil Dead films). The key is to make sure it is as easy as possible to keep your hands up, then they'll tend to do just that.
If you are building good habits they will be reinforced every time anyone throws a punch at you and every time you throw a punch. The idea of teaching yourself to keep your hands up by having people hit you really hard in the head doesn't work on a psychological level.
All that happens then is dropping the hands gets linked to something powerfully negative - getting hit really hard - but keeping the hands up doesn't get as strongly linked to something positive. If you got drilled and it hurt lots you'd remember that way more than the shots that bounced off your guard with no effect.
If you bring the contact level of your sparring down to the point that the mistakes don't have a huge consequence (ie you're not getting rattled every shot), then you will notice the times it goes right more than the times it goes wrong.
This allows you to build and reinforce the good habit. Once this habit is set you can then begin to increase the sparring level again - often to much higher than it was originally but everyone is cool, calm and collected, playing with good guard and good punch recovery.
I've seen this time and time again with people i have coached, at my own gym and on seminars. The body won't learn unless the mind lets it.
One of the big differences between what we do and what any other sports do is that
we fight while they play. I'm from the UK and here everyone plays football/soccer as kids. Learning the skills needed to be competitive comes through hours of play on the local fields using tee shirts for goalposts. Look at basket ball, with kids shooting hoops for fun or playing one on one pick up matches with friends.
In martial arts people tend to come in with a fight mentality from day one... whatever their reason for walking in the door. If you are fighting you're not learning, regardless of what your body is doing. This is why so much time is spent on drilling, if everyone just sparred the red mist would descend and get in the way of development. If you can change your relationship to sparring so it becomes a learning tool rather than just a testing tool then you can fix problems like keeping your hands up in a healthy way whatever you are training.