I believe that if you start higher there’s a good chance you’ll denature most of the beta amylase rendering it inactive. This would then require a lengthy beta rest to get what you want. Of course it depends on how high you go on the initial mash temps.
IIRC overnight mashers report very fermentable wort. Of course most are using a mash temp that favors both beta and alpha amylase (~152°). Therefore, the mash will remain in the beta stage much more longer as it is active down to 140°.
Now with all things I suggest that you see for yourself how it will end up. Sometimes the science or theory doesn’t match with reality. Worse comes to worse you’ll just end up with a fuller bodied beer.