Why closing project phase should not be delayed until project completion?

1. useful information may be lost

All Through I did not had to close a project ... the most logical answer for me is #1 useful information may be lost

1.>>>>>>>>>>>>>> useful information may be lost

Once your team complete all the activities, and thus after the satisfation of the client and certificarion from the consultant. You may be able to get the completion certificate through the client. And then the billing phase. After that phase you may aske the closing phase. But in some cases you may de mobilised some aspect because of the start some other project.

useful info about the site may be lost 

Point #1: Is a more appropriate reason. If i have to choose another from rest of the three points i will go for the point #2.

1. useful information may be lost is the right option. Thanks.

My answer is option (1) useful information may be lost

in any case the project will not be closed if it not completed 

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