Recently, during an interview I was asked about how to learn many pieces at once and how to keep several programmes in the fingers. I ended up talking about something which seems simple but can help a lot when you are under pressure.
I keep a practice sheet when I need to get many pieces going or I have to keep a lot of repertoire fresh. I invent different signs meaning that the piece needs more work or that it is nearly ready. I can see at a glance if there are pieces that haven't been worked on for several days and I can make sure that everything is brought up to level by the date I need it to be ready.
Here are a couple of the sheets from this spring when I was getting ready to record two CDs during the tour in USA.
I have found this to be very helpful to put some order into my practice time and keep the motivation strong. Try it for yourself and hopefully it will also be of help for you.