People may make more ADR's than they need far in advance then as their trip gets closer they finalize their familes plans. I presume at that point they start to trim off those ADR's they don't need. I am sure the rationale is "covering all their bases" because Aunt Jessica may want the family to go to MK instead of AK. Having ADR's at each ensures them the flexibilty to modify their daily plans. Screws the rest of us who don't do it but some are overkill on ADR's...Thankfully, Disney can limit some of this activity but nothing prevents someone from making an ADR at 1100 and 1:30 at the same restaurant...I think 2 hours is the window Disney sets limits at.