Training with ballistic calculators

Greetings awesome community
I have a simple and maybe a kind of amateur question
Does anyone here use or still using any kind of ballistic calculators ( like this one ) while on the training field?
If you do, could you share your experience and even maybe some tips and tricks??

Cell reception having improved I use electronic ballistic apps in the field; Strelok pro/BallisticsARC.
My personal thinking (plan B) is a working knowledge of the old(er) school calculators are a good idea. I carry one in shooting bag.

I use strelok pro as well. Love it.

I also use my mil scope and a little bit of math to get distance on targets of a known size.