cb conditional with rating fields

I have 24 rating fields during registration process. They are in 3 different tabs. I like to show the second tab when the first 8 ratings are done and the third when the next 8 ratings are done.

Can this be achieved with cb conditional? I tried with

tab --> if "last field of tab before" is empty --> then hide "next tab"

but it is still visible in registration process while registration enabled. Can it be that a rating field alwayse has a value? Is there a different solution?

EDIT: I ADDED CHECKBOXES TO SEPERATE TABS; WITH RATING FIELDS IT SEEMS NOT TO WORK... THANK YOU

That'd mean you're conditioning the same tab 8 times. You can only condition something once. The last condition applied is the only condition that matters. There is currently no AND/OR usage, but it's planned in a later release which would allow this to be doable.

The rating field uses a hidden input where its value is stored during calculation, but it can never be empty as it'll have a value of at least 0, which is not empty. You'll need to check that its value is greater than 0.