part of me senses that your friend may be onto something. That maybe tactics puzzles ISN't the way to start learning chess for the Adult learner coming to chess late in life, which would be me.
Well, it's up to you, let's be clear about your options though.
1). Hearsay advice from a 1600 player.
2). Any master or coach you bother asking (they will tell you tactics). Not to the exclusion of everything else (de la Mesa style) but that tactics are a core component.
In fact it's a common trap for adult learners to be attracted to the strategy and interesting ideas of chess. They spend years never improving because frankly solving tactics all the time is tedious. So they lack the ability to spot and calculate forcing moves consistently and accurately.
A pretty funny/sad example is the backyard professor. Loves the prose of Silman. The idea that concepts rule chess is exciting... and that's not wrong, it's just if you can't spot tactics it doesn't matter what your plan was, you'll lose pieces then lose the game. All the greatest positional players were excellent at calculating tactics.
The example of the backyard professor is sobering. And the fact that you note that adults are often attracted to the strategy stuff, and that this is a 'trap' to never improve has sold me. thank you. and that you note <spot forcing moves consistently and accurately>...VERy important. I often click on wrong answers when I do tactics puzzles, and wonder why I'm not getting better at getting them right. Its because I'm practicing getting them wrong. I have to focus on increased accuracy. That will be job ONE. thanks for your help.
Wafflemaster wrote <Endgames are also very good for calculation practice. They also stress importance of activity and how the pieces coordinate with each other which is also fundamental to chess. Endgames allow you to finish off won positions and salvage difficult positions. The endgame also forms the basis for middlegame strategy.> thank you. Helpful. I will do as I am told by someone who has consistently impressed me.
that's it. I'm done.
Tactics, puzzles, endgame study. Do it all, with as much spare time as you can put to it. Play heaps of games against players-computers rated 200 above your current rating.
I also play through heaps of pgn files of master games. It is a great thrill to match the moves of the masters. It gives you faith that you are improving.