That system works for an iron engine, but won't necessarily work on an aluminum engine. What if the valves are held open when the aluminum engine is cold? And define 'cold'. On large all aluminum engines, the difference in lash between 60* and 75* could be measurable. I have always used the .005 minimum cold lash recommendation to insure that the engine will start when cold.

So, if the card wants .020 lash and my engine grows .015 to .020 depending on the engine's cold temp, if I use your method, the engine may not start because the valves are held open.