Exchange 2010 SP 3 from Rollup 2 to Rollup 15

I will be upgrading my Exchange environment from SP3 Rollup 2 to Rollup 15. Is there a special process to take in order to have successfully upgrade?  I am guessing its ok to go straight from Rollup2 to Rollup 15

Upgrade Order?

1. Client Access
2. Hub Transport
3. Unified Messaging
4. Mailbox