yeah this is correct I think.

the only way to properly remember kanji is the old fashioned way.
write it over and over again.

preferably with a brush. 

 Yeah
Probably gave people a lot more time to think about what they’d write too. And less rush for the mind and heart. 

 I talk big lol

but honestly
when I write a letter or hagaki I write it out on the computer first 

 Hahaha I do the same. Or shamefully get my wife to write it