How long do you stay on one coaching theme?

There is absolutely nothing wrong with staying on a theme for several weeks. In fact, at U8 it can be useful because the players get to see the same idea in different games and different pictures instead of hearing a completely new message every session. The important thing is that the theme does not become the same practice repeated four times. If the focus is support, you can explore it through 2v1s, 3v3s, directional games and normal football. The question stays similar while the problem changes. I would also expect progress to be uneven. One good Tuesday does not mean the learning is finished. Plan in blocks, observe what the children are actually showing you, and move on when the group is ready rather than because the calendar says this week’s topic is over.