I was offered a single lens to wear all the time (I only need glasses for reading but was really fed up with all the on-again off-again palaver with glasses, especially when I'm out shopping.)
I did try wearing it but did not find it easy to adapt....my vision seemed constantly blurred..so I gave up and went back to my trusty specs. This was about a year ago.
A friend of mine, though, who need specs for both reading and distance has one lens for distance, the other for reading and seems to manage perfectly well.
My theory is it depends how good your eyesight was before you needed specs...mine was really good until I got into my 50s when I started to need readers. I think because it used to be so good, and because my distance vision is still pretty good, I find it difficult to tolerate blurring. People who have always had dodgy vision don't seem to have as much bother.
But what do I know ? Maybe an optician will come on and offer an educated opinion.