Otherwise, dwelling back there/then takes away from the vision and energy necessary to cope with now, meaning you're still not happy with the results from the past and you've blown some practice time or actual playing time in dealing with the immediate now.
So far as completing that story or book you mentioned a moment ago, too much time dawdling or dithering in the past will have an impact on the completion date. Too much time spent reviewing the "could have" and "should have" of the past is the equivalent of taking aim at the future, then shooting yourself in the foot.
Another thing to consider, in case you happen to be coming off a good streak of doing well, being happy, and getting the sense of somehow extending your horizons. This is a good sign that you've progressed, matured, ripened, learned. You're on a good forward momentum. Even so, spend some time in the past, looking for where you left something, or wondering if you got all the value out of an experience, and you're going to make a significant discovery.
Looking back is still not the best idea because you'll see things in terms of the growth and progress you made, then begin to wonder why you were so slow to come around, thinking, you were okay back then, but could have done more. Right. The old guilt spiral.
You try to save going back into the past as occasions to review something you composed yesterday or the week before or maybe even longer than that. When you do, you hope you won't stay in the past for too long. Rather, you'll be transported somewhere, in the manner of Dorothy Gale being transported to Oz. Some of the people and places might appear familiar to you because, after all, you'll have been transported to a place in your imagination, which is fed by your actual experiences and day dreams. Some of the places will surprise you because of the way they seem so real, so convincing.
Some individuals and places you encounter during this transportation will send you right back to LAX, or wherever it was from which you began, in the most literary and literal manner possible, all because of one potentially wrong word or attribution.
This much is clear, going back in the past to review what you've done is fraught with the mischief of one or two words too many, one or two sentences not enough, a judgment coming from you instead of one of your characters, perhaps one or more stereotypes you let creep into the language.
Being at this game as long as you have, making contact with others who have, and your own reading have brought you to a point you once thought was cynical but which you now regard instead as manageable. When you go back in time to review, the greater likelihood is that you will get bounced out of your imaginative venue, but the odds are growing better for you to spot the knock-out place, then figure a way to repair it so that the thing that survives all this time travel is the product of your imagination.
The hidden joy and great temptation for dwelling in the past is the awareness of how, being at this as long as you have, you'll not only find places where you screwed up but good information about how to avoid future screw-ups.
This is, of course, the existential elephant in the living room. You come away confident, then you write something or do something or, with deliberation, do not do something you consider significant. Then, no sooner than you get back in time to deconstruct it or, as they say in the worlds of John LeCarre, be debriefed, than you realize you've got to go back and fix it.