Avoid stopping the flow of the game by halting play too often. Stopping from time to time to make a quick, concise coaching point is acceptable.
If the issue is a collective team problem, then it warrants a stoppage. If the issue is individual, then coach that one player, but let the session continue moving along.
You have to assess whether the problem is a common trend that needs to be addressed.
There must be a part of the session where you DON’T stop play at all, usually the last phase. Only by allowing the players to freely play can you assess whether what you have been coaching is working.
If you are constantly coaching and reminding them to do things, then they don’t learn to think for themselves. You must afford them the opportunity to play without interruption. This is your time to critique yourself and whether what you are doing works.

The ultimate goal is to have independent thinkers as soccer players.
Here are a couple of things to keep in mind when it comes to the coachable moments of a session. They are listed from least intrusive to most intrusive.
Allow the conditions of the game to coach the themes. Activities should manipulate the players to achieve the desired behaviors.
Coach at natural stoppages such as when the ball goes out of bounds.
Coach within the flow of the game with quick concise points.
Coach the individual players as the game continues.
If you have to “freeze”, make your freezes really count. This is your “coaching sledgehammer” that you pull out when you really, really want to drive home a point.