I have only standard extra balls, nothing extra, so I get them from a gift, and from so many right tower shots, as one of the achievements. I believe you get one as well from completing all the shots in Ring Frenzie before cashing that out, which is why you should always play that for all shots.
Other than that, I actually have my rules set slightly harder than default, as I didn’t like how you could unlock all the locks for TTT before locking ball 1. Mine has to unlock a lock, lock a ball, then unlock the next, which is I believe what happens on default for the second time through to qualify for TTT. Also, for ROTK, I made something there harder as well, but I can’t recall what. I limited the shots you could start each MB as well.
I did this right when I got the machine, mainly because TTT just seemed so unbalanced to start as opposed to the rest. Had I known this likely would be a further issue in me getting to Valinor, I would not have, but I have never changed it back, and it’s something I notice blatantly every time I play this at my buddy’s place.
I have two ball DTR set as well. Some think this isn't a big deal in the change, but when you are on ball three and Valinor is waiting (or even DTR some games), the stress level in trying to deal with the 2 ball DTR can be huge, as even making a shot to the ring to knock the other out is not always 100%. I have posts set factory, and clean all my machines frequently, and it plays insanely fast. Orbit shots can be hard to pick up sometimes if shot cleanly.
F'ing love it...