Is it worth it to practice with some sticks a little heavier/lighter than the ones that I actually play with?
I'm not a drummer but I've talked about this with the drummer in my band a bit. So I have some insight but not enough experience to truly provide full detail or necessarily be able to answer follow up questions, though I will try.
Practicing with different stick sizes can be quite useful, typically on the side of practicing with heavier sticks. The heavier sticks will work your muscles harder and develop more strength and endurance than lighter sticks. When you transition back to the lighter sticks, they should end up feeling almost weightless, allowing you to play high intensity parts for much longer before losing your chops. I couldn't speak to there being any value to practicing with lighter sticks than you're usually playing with, though I can imagine ways that it could potentially be useful but I won't speculate on that.
The hardest part about doing this will be transitioning back and forth between the sticks. If you end up on the practice pad with heavy sticks more often than on the kit with lighter sticks, you may end up playing worse, or the sticks could feel so light that they pretty much fall out of your hands. So you would want to make sure that you're comfortable with that transition before you start implementing and find yourself struggling through a gig. If you are indeed on the pad more than the kit, I would recommend using the lighter sticks while practicing also, switching back and forth or ending with the lighter sticks, so that your hands and brain get used to that switch and it can become a subconscious thing. It may actually be good to have several different stick sizes and move around between all of them. This may not have a huge impact, I'm not sure, but could potentially develop a stronger sense of control that doesn't rely on the sticks themselves.
My drummer plays in lots of different styles of bands, from relatively heavy Rock to traditional Jazz, so he actually uses different sticks for each genre, occasionally switching for specific songs for a single band. He's mentioned occasional issues with using his preferred sticks for our band after a period of time playing more consistently with another band but he adjusted quickly enough that it wasn't a major issue and could be avoided altogether by practicing with the different sticks more consistently.
As a last note on the subject, this concept can also apply to other instruments. Jaco Pastorius mentioned in an instructional video that he would switch out the neck on his Fender Jazz Bass for a Fender P-Bass neck when practicing because the P-Bass neck required a little more work on the hands and the Jazz neck then felt easier to play for gigs. With the speed and dexterity required to perform like Jaco, I imagine this was a very helpful exercise.
Again, I'm not a drummer and am only providing advice based on what I've been told. So as much as I trust my drummer's thoughts on the subject, it's definitely a good idea to hear some first hand advice from actual drummers and potentially ask a teaching professional.
Larger sticks will help.
Metal sticks are also good for stick control on the pad as they can be less forgiving - just make sure that you don't use them all the time. Check out JoJo Mayer's DVD Advanced Stick control for the Modern Drummer - he talks about using metal sticks for practicing on there.
Hope that helps J
This depends on what you are practicing.
I believe heavier are better for working out the muscles. I'm using the Ralph Hardimon series from Vic Firth, for example, simply because these are the heaviest I found so far. The important thing is that they have an excellent balance and rebound so they don't feel heavy. I believe heavy sticks helped me to work out the weak hand faster.
Once your grip is firm, you'll be able to play any sticks and adjust your dynamics accordingly.
It might not be good to practice with heavy sticks all the time. They have a purpose and are to be used to strengthen the muscles.
Ideally, you would practice with the sticks you play with.
After working out the muscles for several months, I went to 2B sticks for general practice. They are the heaviest of the "normal"-size sticks. The transition to 5- or 7-size is not noticeable and they still help work out the muscles.