The simple truth of the matter is that it comes down to how earnest an organization is, what their ethos is, and finally... how risk averse that organization is. I say it this way, because a backup/storage admin can't make it happen on his/her own - when you get to 1000+ size estate, then you rely on working together with several other teams. If you all believe that patches must and need to be applied, then it will happen.
I've seen some sites (but in truth not many), where it really is simply treated by all that patches should be, must be, and are... kept up to date. And, sadly, more sites that are not.
If you have a amanagement team that do understand that without regular patching then you are simply storing up issues for a rainy day, then you are in a good starting position.
Draw a comparison... Would anyone in their right mind not regularly apply the monthly MS patches to their Windows estate? Probably not. So I guess there's something in that to be thankful for... that managers have learnt to keep things up to date. I see no reason why NetBackup clients should not be treated the same way, and many reasons why they should be.
Having said all that - and by your tone/approach - I'm sure that you aware of the concept of diminishing returns. For many organisations, staff simply don't have the time - because 'all staff' think they don't have the time. At the end of the day, I think it's a cultural question, and not a technical question.
My angle has usually been:
- if there's a critical flaw - patch it.
- if there's a serious bug - then patch those clients that might be exposed.
- any others - then begin the process of estate wide patching of clients at such a point in time that you have them all patched ready before you reach the point in time where your master/media server patching would put the older clients in to an un-supported position. (i.e. start a long time before hand).