We only make ADR's for the highly popular table service restaurants in WDW. This October, we have them for Liberty Tree, Le Cellier, the H&V character meal, and 50's Prime Time. We've never needed ADR's for most resort restaurants, especially within WL and BC. One would be good for Ohana in the Poly, though. We've never needed ADR's for Garden Grille in EPCOT, nor for the German "beer hall" type place in EPCOT. We are going to Hoop De Doo, and ADR's are required for that.
But we have pretty much walked up and sat down at Le Cellier, Liberty Tree, etc. within 20 minutes of arriving sometimes, in October. This is about the wait you can expect even if you have an ADR.
Some people will say October is really busy. It's nothing like Spring Break, summer or the Holidays. It's one of the lighter months of the year.
Except for Hoop De Doo, the Luau, and other dinner show types of things, ADR's are not reservations, in the usual sense of the word. They merely reserve you a spot in line if you show up by your ADR time. If it's an hour before a table becomes available when you arrive for your ADR, that table will still take an hour for you to get. They do not hold tables for you with ADR's, except of course for the aforementioned dinner show events.
Personally, I wish they'd change this, and make ADR's actual reservations that hold tables for at least a few minutes. Require guests to secure them with a credit card like for the Hoop De Doo, for instance, and levy a certain fee (maybe the cost of a meal for 1 adult) for not showing up for the ADR or cancelling within a reasonable time frame. This would really cut down on the "ADR abuse" that seems to be such an issue, and would better promise guests that an actual table will be available for them when they show up, rather than having to wait in line just the same as those who do not have ADR's.
Also, it depends on which part of October you're going in as to whether you really need ADR's at all. We are going the 2nd week of October, which happens to coincide with Columbus Day weekend and also Fall Break for schools in many states, so ADR's made sense for the most popular restaurants, but not all of them. If you are going between that time and around November 15th or so, you could probably walk up to most restaurants and be seated within 15-20 minutes, easily. The exception would be "Jersey Week", but I'm not exactly sure when that is.
If you do decide to make ADR's, make sure you confirm each and every one of them when you arrive for your vacation, and bring your ADR # with you. Those restaurants are not the most reliable about having your ADR show up on their lists.