You certainly do use up eligibility to get up to speed or a head start on next year. Let me throw out our potential situation next year as a reason it could make since for someone like Jana.
If you look at the C position for next year, we do not have any experienced and proven players coming back at that position. We have talented prospects and proven PF's, and we are loaded everywhere else, but all three candidates are projects, Ice and Jana with no game experience and Amari with limited mop up minutes (at least so far).
So unless we rely on more natural PF's, the starting C and principle backup C will either be two freshmen, or one freshmen and Amari. Normally this would not be the case, a freshmen C would have other more experienced players to practice against and learn from and wouldn't need to produce in important minutes right away. The C position often has the biggest adjustment from HS to college as well, since many bigs don't get to play against many similarly sized or skilled opponents.
Jana might be needed for a significant role right from the start next season, so from that standpoint getting experience even if just in practice, and up to speed with the program, could advance her preparation for a role in her first year. I am pretty confident Ice will be relevant from the start, but she is coming off an injury, and Amari so far hasn't shown she is the answer to anything.
Somebody like KK or Ashlynn could come in next year and play some important minutes, but the team has the luxury of bringing them along slowly like an apprentice as well. Our C candidates are not in the same position, we really need two out of three of them ready to go next year to avoid having to play PF's instead.