I tend to deliberately overwrite to begin with, because taking things out is harder than adding things in, especially if I've forgotten those things, or hadn't thought of them in the first place. However, if I'm cruising along and something comes up that I just really want to put in a spot that was a few pages ago, the last thing I want to do is stop my forward momentum, go back, and worry about adding it in.
What I do is I make notes about the particular item. Sometimes they're brief notes, sometimes they're very detailed. But after I've noted whatever it is I want to add in, I keep moving with the rough draft. Once I'm done, THEN I'll go back and add it in.
The curious thing is, after I finished my latest WIP's rough draft, when I went back to add some of those things, I realized they were no longer relevant. By finishing it out, I had either found better places to add those things in, or discovered that their inclusion would not have been a benefit to the WIP overall.
So my advice would be, note it down, but keep moving forward. Come back to it later. If you still think it's relevant and necessary, work it in then.