Their palettes are very comparable to Kryolan, Cinema Secrets, and RCMA foundation palettes, in terms of that they are highly pigmented, rich and easy to blend, and you can sheer it out to how you want it to look. So very little product will go a very long way
For example, you only need a pinky fingernail sized amount for a full face.
The only downside to these foundations is that people tend to waste a LOT of product as they decant too much from the well at once. Always decant a small amount, if you need more as you go along, decant a bit more.
I definitely don't recommend using brushes, sponges, fingers etc directly from open-styled palettes like these, as you will cross-contaminate it with bacteria! And your palette will only last a few weeks to a month at best. You can tell the foundation is turning due to bacteria, is the bad smell and the texture will be stiff and cakey, not thick, rich and creamy.
All the Pros that I know of and have worked with, all of our open-styled foundation palettes have lasted years and years with absolutely no problems, as we always decant.