The large tables do have a number of updates / inserts during the day but this varies depending if a campaign is being run or not.

I do an sp_updatestats on the tables before the nightly index jobs.

Indexes may or may not be rebuilt (therefore creating new stats) depending on the fragmentation threshold at the time of the job run, so an sp_updatestats may be all they get.

Auto Update Stats is on for each DB involved.

So assuming it is out of date stats then:

1. Would an extra sp_update stats run during the day help (I don't think this locks anything does it?)

2. Or would an UPDATE STATISTICS() run nightly with as high a scan % as it possible be better?

or both...

Is is common for companies to run extra stat updates during the day?

I am still trying to fully understand SP_UPDATESTATS and when to run this command over an UPDATE STATISTICS command with a scan %