I just traveled solo and it stinks to wrestle with ADRs. In my limited experience (only there for 4-5 days). there was not a noticeable difference when I looked for ADRs for 1 vs. 2. I generally found what I wanted when I entered 1. If I got a reservation and it wasn't the time I wanted, I'd search for close by times for 1, then 2, and then 4 - and nothing ever shifted. When I didn't get the ADR I wanted at all, I did the same thing (change times, # of people) and still things didn't open up for me. So, it could be that the places I looked at (resorts, DHS, EP, DAK) weren't going through that issue at the time (I don't doubt the folks who've had good history adapting their party number and finding something suddenly). I did end up booking 1 ADR for 2 - I placed that in my TP reservation finder as a default, thinking that maybe they'd find that instead of 1 (I didn't try 1 as a control or anything) and that ADR did become available the week of my trip. I booked it and then modified to 1. Good luck!