it's not uncommon to see (qualified) pilots taking off with little or no preparation...just the students seem to plan properly.
This sadly is very true, and why I actually think what you're doing is potentially quite useful.
But, I do also think that professionalism includes staying current on all the tools available to you - then you can pick the one most sensible at any given time. More than once in my life, that's been a whizz wheel, or mental arithmetic.
G