As Flipaclip is designed for phones and tablets, which by their nature have limited resources compared to laptops and desktop PCs, I find it best to split an animation into several smaller sections when working on a project. So I would have three projects of no more than 20 - 50 frames, rather than one large project . This also makes it easier to keep track of things, as well as being closer to the way one would work on a traditional pen and paper animation (where you could only really work on a handful of drawings at a time).
With this in mind, it would be great if the project window had a feature whereby you could group several small projects into one master project. This would make project management much easier. If, in addition, one was able to render all the projects contained in a master project into one movie (or image sequence), that would be fantastic.