Like any other new food, you have to introduce it slowly and start with tiny amounts mixed in with other stuff that they already like. Its worth the time.I thought I was a great idea too.. save me lots of labor... but my guy turned his nose up [emoji37]
I tried dumping a big pile in at first and it would wither and dry out in the sun. After a couple of months of mixing it in with other favorite foods, they'd walk right up and eat the whole pile.
It also depends on the time of year. The middle of winter when their appetite is lowest isn't a good time to try new stuff for an outdoor tortoise. Your success rate will be much higher in late spring or summer.