It may be fun and even seem effective, spraying everything down with some sort of aerosol or even pump-sprayed lube. But for your mountain bike, just keep it away. Especially for those out there with disc brakes, but really it tends to cause more harm than good on all bikes.

Spray lubes do a great job of forcing droplets of oil into the chain, no doubt. But they also tend to coat everything around and behind whatever you really want to lubricate in a fine mist of oils. Not good. Even if subtle, excess lubricants on a bike tend to collect grime. On a drivetrain this can actually lead to a dirtier system than prior to the spray lubrication. The rest of the bike just collects unsightly dirt. On a disc brake, even just a few droplets of lube overspray can ruin brake performance as the pads soak up and spread around the oils. The only sure cure are new pads and freshly cleaned rotors - its easier and cheaper to not contaminate them in the first place.

Stick with the drip lubes. Leave the spray stuff for door hinges, not your bicycle.