More thoughts

Correspondence play.
From 35 finished turn based games I have won 32, drawed 1 and lost 2.
A real nuisance is that EVERYBODY continues to play thru no matter HOW MUCH material they are behind. What do they think with 3 days per move? Since I started with chess 8 years ago I haven't stalemated a single game. Not even under time pressure. I really hope that matters become better with higher rated players.
My rating rises terribly slow so it is difficult to get higher rated players. At RedHotPawn you can't even chose the rating of your opponents before you have finished 20 games.

The plus side is that I get a lot of endgames, I can experiment with my new acquired strategical knowledge and I can check my opening play. Since I rebuilded my repertoire 4 years ago, a lot of book lines are unintentionally replaced with my own fantasy lines.

More thoughts about piece activity.
Or maybe I should call it reshuffling of my thoughts.

Home.
A piece must have a good home from where it can work. For a knight which has a short range this is different in comparison to the longe range pieces like the rook, bishop and queen.
It can take a lot of work to eliminate all potential attackers of the home to make it secure. Some times tactics are needed to get a knight to his home.

Pathway.
A piece must have a pathway to the enemy camp. This is not needed for a knight since the beast can hop over any piece. Opening files or diagonals is the tool here.

Domination.
A pathway to the enemy is double edged. You have to make sure that you can dominate an open line. If not, your opponent might use it against you. Often the only use of an open line is to trade pieces. You have to know which trades are favourable and which not.

Pawns.
The primary constraint of piece activity are the pawns. With pawns you can create secure homes and pathways.

Acquisition vs. prevention.
There are two sides to each topic. You can eiter try to obtain advantages for yourself or to prevent your opponent from getting or keeping them.

Activity.
Piece activity is the nec plus ultra of strategical play. But what makes a piece active? As Blue Devil put it, is there an unifying idea behind the different types of activity?
I guess it has to do with targets.
If it is concrete, we call it J'adoube's Law of Tactics: Good positional play yields good tactical opportunities.
Most of the time it isn't that concrete. If white is able to maintain a knight at d6, it is favourable in 99% of the middlegame positions. No need to bother beforehand how this advantage is going to materialize.
If the play is not about targets it is about creating a new home in the enemy camp.

Basically I have said the same as in the previous post. I see it as trial and error. I'm still hoping for inspiration. Hence comments are more than welcome!