USO... tables - new 'Best Practice' system

Question: We have a newly built sandbox system (start of project) and I was assuming I would have to go in to SU25 to do the steps to populate the USOxx_C tables. (I’ve never been on an implementation from scratch so never done these steps myself before). However these are already 'somewhat' populated.

As it is a system migrated from SAP’s best practice system this probably explains why this is already done. However, when I look at the content of USOBX versus USOBX_C there is a difference on the number of entries. USOBX has 359,370 entries -30,000 more than the custom one.
USOBT has approx 190k - 60,000 more than the custom one.

Is this an error on SAP’s best practice system?
Should I run SU25 steps anyway?

Answer:
Does anyone have any input on this query?
I've just had a look at SU25 and step one was done in Jan 2005 and Step 2 in May 2004 ?

Answer:
Sorry to bump this up again but I have performed the SU25 step 1 in our sandbox system. The no of table entries are still not in sync, although there is less of a difference between the two.

Has anyone who has completed SU25 step on a system been able to confirm that, after this step, the no. of entries in the custom table matches the standard SAP one?