I have been doing these 50% to 90% cycles since 2008 alot. My three batteries are just now staring to fall off on their power performance. Even if I do a bunch of full charge states... So I guess they are getting closer to their end life...
Now if you do this to your standard car/truck start battery you find you really only get one cycle of going down real low on the battery charge.
I usually have to replace my truck start battery here about every two years and with my Ham Radio setup I am forever running the start battery down in the truck. Over this last winter I have having to jump start my truck several times over the months. My 2KW generator is secured to the truck bed so I have 120VAC on me all the time and can hook up my portable battery charger and get some juice back in the battery so I can start the truck haha... They gettin used to me doing this in my local WALMART as i sit out there waiting for the wife alot and can't leave my Han radio alone...