[IKE]

Nathan,
Several teams in Michigan still build practice robots, though several have found that the access periods and competition are sufficient to be competitive. It depends how much time you plan on practicing. In theory with the access window of 6 hours with no session allowing for less than 2 hours, you get 1-3 robot level working sessions.
If you plan out the sessions and have someone paying attention to the clock, you can achieve a lot in those sessions. If you are organized, and plan well, then the "need" for a practice bot begins becoming a diminishing return situation.
If you are used to doing a practice bot, I would recommend doing one again and then evaluate at the end of season whether you should do one in the future.