I've found that the MORE you exercise your mind and eye / hand flying, you get better and stronger and have more capacity to handle things
using automation all the time is like using an escalator instead of taking the stairs. and the day the escalator goes Tango Uniform, you will be out of breath and have NO spare capacity.
one pilot friend of mine said: you really aren't ready to be an instrument pilot or ATP until you can hand fly an ILS to minimums while eating a hamburger and getting the phone number of a DARN good looking Female Flight Attendant.
All while doing your logbook.