they can be left alone for a while,does depend on the bird,and the time your away.
Also foraging,which can keep them busy for hours if you are going to do that.
My first one was the kind that couldn't be on her on,she would wait for me to come back and then not leave me alone.
She would stay in the same position when i left,she was that bonded,so i got her a partner,which turned her persona 180.(so glad at that!)
My 3 was also like her and she to got a partner now.
But i would say that they require a fairly large cage as they are very active birds.
Trough i am the type to say it is better to have 2,but i know not everyone agrees

One of my cages has an uv lamp,i don't know if it is really needed but this is the cage furthest away from the window,so i like the thought of it.