Besides, the notification is for notifying us, doesn't mean we need to do it within N minutes, it can wait until your Very Important Business Call is over or whatever. As long as it's done before it starts to get overly humid and starts to smell.
Very few things need my attention now.
On all settings except timer, my dryer is pretty much useless. I set it to dry my bedsheets and towels with bulky item preset, max dry (who chooses minimum dry for anything?) and it'll say it'll take 1h30m, ends up taking 30 minutes, and everything is still wet, despite it having a "dryness sensor"
I've just started using the timer function on the dryer and it's been mostly accurate, plus or minus a few minutes perhaps.
Fortunately, we usually just throw clothes in the dryer before bed, so we don't need a system to remind us when it's done — if it's not done by morning time then we probably need a new dryer!
I'm not sure this is true anymore, first you usually do different programs depending on what you put into it, and modern washing machines also automatically adjust the washing time depending on how much you throw into it, at least our ~2 year old one does, I'm sure others do too.
I basically never know how long time it will take, sometimes it takes 1.5 hours and sometimes 3 hours. Our washing machine is further away from where we can hear the melody, so having a notification appear on the phone when it's done is actually quite handy, at least for our situation.