I don't think its an unfair practice. I think it is a huge investment of time thats for sure. but unfair no. everyone has the same opportunity to do this and i never have either to be honest but i don't think its unfair. Also why would anyone walk at 11 months i don't understand that at all. 7 months yes but why at 11 you have the home resort priority so technically no one has the room before you anyway as long as you book at 8am the day of your 11 month window if you own and want a high demand time resort and room type.
1) you are holding rooms that you don't intend to use, which interferes with other owners who want to book those nights. it's at least a little rude.
2) at 11 months out, it makes sense only in a very few cases: booking AKV club level or even relatively scarce villa types like AKV value, BLT standard, or BWV standard during new years (or food and wine for BWV).
the whole point of walking is that if i want a reservation that starts dec 25th but wait till jan 25 to try to book it, other home resort owners have had a shot to book dec 25 for the previous week (i.e. someone booking dec 25 as part of a reservation starting on dec 19 or so when they call on jan 19).
3) walking at 7 months seems silly to me. home resort owners can jump in and take nights away from you at any time. if demand isn't high enough for home resort owners to take the villas, you'll probably be fine to wait and book it (or waitlist) at 7 months out and it will come through one way or the other.
hopefully, if others think as you do, it will be considered abuse of the system and
DVC will make changes to discourage it (whether by limited changes to reservations or starting to charge for calling MS or something).