The title may not be the best, but I have to start somewhere.
Artifacts of Edits to Existing Schematics
There is an rather annoying artifact of editing the schematic of a reasonably mature project. I believe that operations like adding a hierarchical page and moving parts from other pages cause difficulties with the existing PCB layout.
For reasons I don’t fully understand, when making changes to an existing schematic, the timestamp on component insertion changes or a new component is created. Consider that U1 exists on Sheet 1. Moving that via Cut/Paste or possible creating a new sheet and Inserting another sheet contents, results in another instance of U1. The use of U1 is correct for the schematic, it is now just located on another sheet. There will be only a single instance of U1.
When Updating the PCB from Sch, U1 comes with a NEW timestamp. This results in 2 instances of U1, one already placed and possible routed, and another floating U1. This is not a disaster, but when there are 20+ components already routed, there needs to be No Change to the PCB. I believe the issue is the timestamp differences.
What I propose, is a feature to reduce the significant impact on the existing PCB layout.
I will use a manual example to clarify my limited understanding and propose a solution.
A tool could be introduced (popup?) which lists
Retain Footprint Update Footprint
U1 (old timestamp) [ _ ] (new timestamp) [ _ ] ← Checkboxes
If the user selects Retain:
COPY the new timestamp into the OLD U1
delete the new instance of U1 footprint
If the user selects Update
The Old U1 footprint is deleted.
It would be useful to have a option to select Retain All.
Alternately, in PCB, when update is performed, if there are timestamp differences, just update the time stamp and be done with it (assuming the same footprint is used). No need for the popup. I may not be recognizing other side effects of this operation.
Alternate #2: have a PCB Tool feature SYNC, which lists timestamp differences, without making changes.
In summary, anything that can be done to reduce the artifacts of schematic edits on existing layouts would be a HUGE improvement over having to manually deal with the duplicate footprints.