My understanding is that all fields for all screens will be in one table (vertical rather than horizontal)
This sounds like you will end up with what is known as an EAV design, Entity-Attribute-Value.
Obviously performance will be an issue among other things.
EAV is generally frowned upon, because far to often it is a cop-out from doing proper data modelling. However, EAV has its place, and I have used it some corners of applications I have worked with. I would not like to make a centrepiece of the design, though. And least of all if performance is of interest.