Not true.
Don't go through FULL cycles regularly as batteries in general have a certain quantum of energy they can can give, but, unless I am mistaken, its good to let a phone battery discharge every month or so (and after a few charge cycles when new) so that the internal battery calibration is kept on track (no not the voodoo battery calibration discredited by google) and also, it gets the (static) electrons normally not used in light discharge cycles moving throughout the battery.
I could be wrong but this is what the battery university (?) Site used to recommended.
Please feel free to correct if this has changed!