One could raise a concern that this would possibly unfairly harm teams in leagues (usually middle-level teams) who don't have easy weeks because of teams tanking for the cup or numerous bots, whereas teams at the top often have one or two weeks where there is a tanking team or later in the season teams throwing games to keep their Cup run alive.
With that said, I do think it's a little gimmicky - I think in a perfect world, speeding up training should be something applied in every week or none at all. I also, unfortunately, am of the opinion that we're too likely for the option in that case to be 'none at all' so I think your proposal would be an improvement over the status quo, even if not the improvement I'd consider ideal.