I have many good rentals, cards that go for 1-10 DEC a day for 0.1 DEC for example and hold many of those for days, weeks or even month.
But I mostly rent regular cards to play with, not for power, so I'm sure with GF power cards that make the real big bucks there will be more cancellations. However if you rent during the season you can still make the daily quest and DEC/Win, getting just the 3 chests more at EOS is probably not worth it.