I've enjoyed watching some YT's from Darren Alf, AKA as "The Bicycle Touring Pro". He's had a few useful tidbits based on his near 20 years of continual touring. Among them is that he rarely rides (self supported gear) more than 40-60 miles in a day. He's certainly fit enough to do more and often will extend out to 100 miles or so, but not when he doesn't have too. He also tends to sleep late if he's solo, that accounts for less mileage and he spends a lot of time somewhere charging electronics (that support his videos, which is how he earns a living).
Another is that the first 4 days of a tour can suck and that's very true as your body gets used to being on a bike and you get into the rhythm of riding every day, camping, being outside 24/7, etc.....