Here is my take on this subject...
kotag kris,
If some one is in US, and is working on EAD and for some reason want to wait to get passport stamped then there may not be a bit problem. But here are the issues on this subject:
1. Previous statuses H1, EAD, AP etc. are invalid and need to move to new status as early as possible. For e.g. if some one is working on H1 then after I-485 approval they need to update their status with the employer.
2. Let\'s say some one is outside US and want to wait for a very long time to get back into US and get PP stamped. I see some very serious problem with this! As "rsrgc" wrote GC is for permanent residence here in US. After getting approved the person is expected to move the residence to US and settle here. If it doesn\'t happen INS can revoke the GC (note that if a person with GC travels outside US without travel permit and stays longer than 6 months then in most of the cases INS can revoke that green card, unless there is some extraordinary situation etc.)
3. Now let us think that some one got AP and went overseas and comes back before that AP expires, but at POE finds out that their pending GC was approved few months back and they didn\'t knew about it. Then it may not be a big problem because they didn\'t know about the approval and based on that invalidation of AP.
Normally attorneys advise people to come back and get passport stamped as early as possible. More the delay, it is more subject to scrutiny at POE.
- PCee