Do you ever coach tackling technique on its own?

A short isolated block can be useful if there is a specific technical problem, but I would get opposition back in quickly. For U10s, I want them learning how to arrive, slow down, get balanced and choose when to tackle. Those details make more sense when an attacker can actually change direction. You could spend five minutes on body position and the tackling action, then move straight into 1v1s where the defender gets repeated chances. If players are diving in, the bigger issue may be the approach before the tackle rather than the tackle itself. If they are pulling out, give them lots of safe, competitive repetitions so contact does not feel like a special event. Technique matters. Timing and decision matter just as much. I would use isolation to clarify a detail, not make it the whole lesson.