I'd really love if I could customise my drives not based on my past driving but to build in a buffer time (like add 5-10% to expected journey time, for example).

Part of the reason I like Waze so much is probably related to the fact I have ADHD and the instructions and clearly stated ahead of time ("...in 800m, turn right") and then repeated ("...in 200m, turn right").

Possibly because of that ADHD, I really struggle with being on time and poorly estimate how long things will take me. I try to build in a mental buffer, but because I know I've done that, it often doesn't work. This also means any past data on my driving is likely based on a journey where I was running late!

A navigation app where I could toggle on a buffer would be best, especially as a percentage which is not so intuitive that I'd unconsciously reverse-engineer it and mentally deduct those extra 7 minutes or whatever it might be the app added on to my predicted driving time.

I expect that seems a highly specific feature request, but it occurred to me that the Waze features that appeal to me might be ADHD-related and therefore, the app might actually have a higher than average number of ADHD users.