On a daily basis, they can be left alone for work hours (8 hours or so) and will be ok, although it's a good idea to get an extra large cage, place it where she has a view out a window, and possibly leave a radio or white noise machine on if the house is really quiet if she will be alone that much. And of course, you should try to have her out when you are home so she can interact with you or play on a playstand.
It IS important that you get her used to being left alone gradually. Suddenly being left alone during the day when she expects people to be around is very stressful, so you should start with leaving her for an hour and go from there. If she doesn't forage much, you can also start trying to hide a few treats around her cage when you leave.