I’ve been writing a 19x19 FOR BEGINNERS series here on OGS. In Part 5, I tried to tackle some of these questions.
The answers are complex and multi-faceted - because so much depends on the skill level of the players involved. However, I tried to get down to basics and show that all these complexities are an outgrowth of the underlying efficiencies which shape the dynamic of the whole-board game.
After describing the underlying mechanics and the goals at each stage of the game, I tried to demonstrate that through 3 different games at different levels:
Beginner game: here two players (22 kyu / 24 kyu) focus more on contact fighting, and (mostly) ignore the underlying efficiencies of the game. However, one reaps the benefits of direction of play and efficiencies, while the other gets pushed into the middle.
Intermediate game: This is a peaceful game of GnuGo vs GnuGo - rather than fighting to capture, both opponents make the most of the underlying efficiencies inherent in the game to convert the potential gained in the Opening into decent moyos in Early Midgame.
Advanced game: This is a game between two 9 dan pros. Much like the beginner game, the contact fighting starts early. However, these two pros show that they know when to focus on local fights, and when to zoom out and prioritize whole-board play. I use the metaphor of Red Light / Green Light to show readers when to focus on protecting local groups, and when to zoom out and return to whole-board stage-of-the-game priorities.
Hopefully this set of skills will help you develop your own ways of transitioning from the Opening to Early Midgame. Good luck