As a thought experiment, how long should a toast remain on the screen? Ideally you want the user to have time to read it, but since you don't know how long it will take for them to glance up, and you don't know their reading speed, there isn't a safe bound.
I ran into this with my son just today, he is working on his reading speed and we were using a new app together. I kept showing toasts and he was struggling to keep up with them and found them to be distracting. I ended up reading them aloud so he could keep up. A more persistent message would have let him succeed without extra support.
MacOS and phones do this well, the toast is up for what feels like enough time to read it, but if you didn’t catch it, you can slide open the notifications ui and see all the previous ones for as long as you want.
I ran into this with my son just today, he is working on his reading speed and we were using a new app together. I kept showing toasts and he was struggling to keep up with them and found them to be distracting. I ended up reading them aloud so he could keep up. A more persistent message would have let him succeed without extra support.