so I just finished my first proper Any% run, which should be ready for submission tomorrow. I timed a few things to elaborate timesaves for the Any% category and this is what I've found:
(1) Obviously, taking the optimal route from stage to stage with the overworld bus, spamming that dash button and avoiding obstacles like those mountains at the bottom.
(2) Obviously, the final boss which is the only skill based level (apart from being required getting at least 1 star in each). The meteor RNG is a big thing, but nonetheless since theres no order RNG it's all about planning and reaction.
(3) Skipping hut dialogs. You don't ever need to talk to the onion man. Just enter the houses, dash once to the left, press A to leave and the next level spawns.
(4) Skipping stars. I timed that it is a tiny bit faster to not get all 3 stars in a stage since it makes skipping the score screen (by pressing A) available about 1 second earlier if you just get 1 star instead of 3. You need 74/87 stars for the final stage to spawn so you have room for 13 stars to miss which could therefore grant about 6,5 seconds of timesave over the entire run.
(5) Do a playthrough before the run. If you played on a "fresh" system, you constantly unlock new chefs and unlock new stages which wastes time.
(6) Be prepared for the alert windows. There are only two. One in the turorial which says "Press (?) to switch chefs" and one in 1-1 which says "wash dirty plates" which stop the time. Make them vanish asap.
(7) Running on PC. The current WR holder for solo any%, Prankhan, played it on PS4, while I played it on PC on an SSD drive which makes it uncomparable due to load times. Just compared stage 4-4 and the load time was 2.5 seconds for me while it was full 8 seconds for him. So not considering potential differences in stages, just extrapolating that would be 30 * 5,5seconds = 2:45min. No idea about XboxOne or Switch loads.