Generally if a pilot forgets to do something or something is broken on a helicopter, bad things happen.
Not having the collective lock on, or not guarding the collective can clearly have undesired consequences as pointed out by Gordy (always hard to look at those pictures), and yes no one gets everything right every time - ref Eurocopter or any of them. I still do believe that they try to at least get it right, and until otherwise instructed by the manufacturer or a regulatory authority, following the RFM is the industry best and safest practice.
I talked to a couple other 350 pilots and they indicated a test at full flight position is their sop. I also looked through RFM's for the B, BA and B3 but couldn't find any other procedure (revisions might not be current though).
Best advice - guard the collective (lock and hand), follow the RFM.