Maximum number of iTunes accounts associated with one credit card?

Question

We have a 20 person sales force and will be updating their iPhones and iPads to iOS 5 at a meeting in February.  We want each sales rep to have their own iCloud account for backups and storage.  So, we created 20 new iTunes accounts for each of them using the same company credit card.  To avoid any problems when we do the rollout I wanted to find out what the maximum number of accounts that iTunes allows you to register with one credit card?
Background Information
Currently, our sales force uses a company ID and password to download apps.  This allows us to keep the accounts and location settings restricted for security purposes in case a device is lost.  We have since created 20 new user accounts under one credit card for our sales force.  I did not do this, but worked closely with the individual who set them up.  They shared that iTunes only allowed three accounts to be created per day with the same credit card - I assume that's for security purposes. 
In the end, all were able to be registered without a problem.  My concern is that when we update the devices, which will be over a period of 1-2 days, will there be a limitation to activating accounts under the same credit card, as there was when we created the accounts?  I'm doing the research now to avoid what could be a significant problem if not properly prepared for.
If there's another solution for this, please feel free to share.  Our objective is to remove the reliance on the company computer for syncing and give the sales force more freedom.  We will still be locking the location for security purposes in case the device is lost/stolen - the iTunes password will be shared between the company and sales rep.  They also won't need to ship the device back to our office if there's a problem, as they would be able to restore with iCloud.
Thank you!

Answer 1

Thank you for the reply!  That is helpful to know.
My follow-up question is this: we somehow managed to add 20 people to one credit card within one month without any warnings.  Should we anticipate encountering a problem? 
In the interim, someone in our office is going to try and log into iTunes separately with each of the 20 accounts and download an app to see if there are any problems.
Thanks for the help.