Has anybody been banned who ONLY gave themselves unlimited practice plays and used ONLY the plays they won from practice?
My theory is that you can do that safely without fear of ban, (unless Nintendo set a threshold that is impossible to cross for each machine individually. Example: There are only 5 practice badges in the machine which each require a drop of their own, with 5 practice drops you could win a maximum of 5 practice badges, you win 99 practice badges and flag yourself for ban)
Unlocking the machine always seemed like a great way to get yourself banned. Think about it: There is no record of you purchasing anything, you unlock the machine and win a bunch of badges, and as soon as you're done it immediately sends a record of you winning badges to Nintendo, an absolute IMPOSSIBILITY without the use of cheats.