I suppose this must have been discussed in the past, but I haven't been able to find anything relevant by searching for it:

When you are doing your weekly review, how do you deal with the case of coming across projects that trigger you to start a planning session, thereby disrupting the flow of the weekly review? Do you succumb to the temptation and interrupt the weekly review, thus killing the spontaneity of brainstorming etc., or do you carry on with the weekly review regardless and come back to the project concerned at a later time?