Ok, my opinion and prior check-in experiences is most definitely different than what most are saying here. All I can say is I have had many trips and utilized both methods of checking in. Prior to the pandemic and prior to the change in how Disney charges you $200 for charging privilege's(You cant even use online-check in unless you agree to put a card on file and have them charge you $200 even if you don't want charging privledges) , I used to always do online check in. It seemed easier and more convenient but these were also the days when the Magical Express would deliver your luggage to your room for you so it made much more sense to skip visiting the front desk and hit the parks immediately without wasting time. Anyway, for whatever reason, all those years of using online check in , my room was never ready for like many many hours after I arrived, and maybe now that I am older, I really don't like that, esepcially since I have to lugg my own luggage there, I prefer to quickly unpack and fix my room the way I like it sooner rather than later.
So, all of my recent trips, I decided to do something different and go back to physically checkin in person. Initially, the main reason was due to my dissatisfaction with the charging to the room change as I don't want all those preemptive banking charges on my bank account. Well, all I can tell you, is that since I have switched to desk check in in person, I have never waited longer than 15 minutes for my room. This includes all of my recent trips post Covid which include stays in 2024, 2023, and 2022 ( 4 trips in total) as well as my 2018 and 2019 trips.
Now I don't dispute what everyone has said about rooms being assigned in advance...however all of my front-desk experiences have given me the distinct impression that the cast member who were in front of me has the ability to facilitate the process for you to have a room ready in a timely manner based on my interactions with them. So, while there may be no guarantee that a room will be ready for you in a timely manner by doing in person front desk check-in, that has been my experience every time. So, if that was something that was important for you, I would personally recommend it.