now, i found many people said they do not like so often software upgrade.
as a software designer, i want to ask how often do you think software should have a upgrate?
as a software designer, are you making money or just doing it for love?
oh, there is one more factor: etiquette. if it contain bug, you are "karma-ly" responsible to fix it. as fast as you can, and if you are not good at what you are doing -- as often as you can.
my own experience, for features, if the money is coming in, we'll do it. as often as we can. more work, more money. even if it mean non stop updating.
for bug fix, once the retention/warranty period expired, they are on their own, unless they sign a new maintenance contract.
Upgrades are required for stability and for new requirements, so it would depend, on how stable it is and how secure it is, as well.
Of course, once an upgrade is done, its possible it could be unstable in some places again, so upgrading requires rigourous testing, before deploying it.
What is an upgrade? Some upgrades like new versions fix problems that have been beta tested. Other upgrades employ new features that allow your computer to work (Os software) along with newer software which it did not originally work with to begin with. So unless you are installing a particular application or using your computer for that matter in a particular way why install it?
This leads back to the original question how do you really know what the upgrade is doing and why? Could an upgrade actually be a downgrade for your computer? (for example make it run slower for the sake of say security)
Upgrade is for new features and bug fixes.
It depends on the software. Important things like anti-virus should constantly be updated, while things like drivers usually don't need to be upgraded unless they offer some significant improvement or they are required to run something properly.