Every person will have their own thoughts. Personally on a large meat like a butt or a brisket, I rub wrap in plastic wrap, let set 2 days in the fridge, start my smoker, bring it to temp and/or get the pretty smoke puffin, then I unwrap, re-rub and put the meat on. I always heard salt in rubs causes dehydration, the drawing out of the moisture you want to say in the meat. I usually use light brown sugar sparingly on my pork to seal the meat. It will encapsulate the skin as it liquifies then caramelizes, crystalizing, creating a delicious outer skin to help hold those juices.
Small meats, ribs, turkeys, loins, chickens, etc I just sprinkle with salt and pepper, maybe go wild and use some onion and garlic too. I have in the past sometimes rubbed a loin or two, ( a pork loin!), and the out come was delightful. I like Tony's More Spice on my fowl skin. There are also some tastee recipes here for home made ones also.
So its all about your whims, your wants, your time, your techniques.
I have never rubbed a piece of meat which it did not bring some additional flavor to the party. I do rub it though, I learned long ago, to massage the spices/herbs into the meat, just like a back rub. I also do the 2 day wrap in the cooler.
As to the mess, you need to do a better wrap, don't think any of mine have leaked, course now the mojo is on me, the next one will for sure! But think of it like when eating crawfish, its ain't good till the juice is dripping down your elbows.