Auto Entered Data impact on Optimization

I have a rudimentary question about optimization logic. I have been re-writing the database I use to run my cabinet shop.  In order to minimize overhead I have eliminated as many calculated fields as possible.  The calculations that do occur now are script based and, for the most part, are performed on the server side before downloading to iPads in the shop.   There are not a lot of users at any given time and probably 300 fields in play for any given cabinet.

My question now is about the overhead associated with Auto-Entered Data.  Many of the pieces of math I use never change.  The thickness of a drawer bottom, for example, is always 12mm.   When performing calculations that allude to this thickness would I be better off to populate the field with a script just when I need the data or would it be more economic auto-entered values?

Edited December 13, 201510 yr by Jarvis
enhance clarity of question