I don't get the logic to leave it in for long but then pull it for shorter ones. if it's ok for a long one it should also be ok for a short one. The flag stick doesn't know your lag putting or not.
And so I guess....from afar your put isn't important but from 7 feet your putting for the win at the Open?
Many of us once had the flag tended on longer putts so we could see our target easier. Leaving it in on the long ones is the same for me. I'm not going to rehash the Golf Digest Tom Mase study, but I find the evidence that leaving the flagstick in will reduce the chances of making putts that don't strike center flagstick(most putts) very compelling. This year I have now had 7 or 8 long putts or chips deflect off the flagstick and finish less than 18" away from the hole. In my judgment, all but one of those would have gone in had the flagstick been pulled. That has happened to me hundreds of times over my golfing career while I have only holed maybe ten shots ever that struck center flagstick that were moving way too fast to go in without the flagstick. We also have a lot of windy days here and the flag flapping in the wind is distracting inside of 20 feet for me. The shadow in my line is also a distraction.
If leaving it in offered any advantage the vast majority of PGA Tour players would leave it in for all putts. Very few do.
The other argument that speed of play is faster with the flagstick holds no merit. We played as a fivesome yesterday with everyone walking and finished in under 4 hours. The flagstick was pulled on 17 of 18 holes.