> Dealing with multiple library changes at once is an order of magnitude more difficult than dealing with them one-at-a-time.
From my experience exactly the opposite is true. Compare uprading Slackware to keeping an Arch Linux running. With Slackware, I have to sit down for an hour, do the upgrade, read the notices that come along with it, maybe see if it will break any of my custom packages. This happes once or twice a year (security upgrades are completely painless as they don't break things). With Arch Linux I need to do that every day. If I don't have time to do it for a month, the system is basically broken beyond recognition...
What I'm advocating is not analogous to the ArchLinux model, partly because I don't think we should stop supporting old versions and I don't think upgrades should be essentially required the moment something is release.
I'm fine with having the odd out of date version of something, I'm just saying: be incremental about keeping your stuff up to date.
From my experience exactly the opposite is true. Compare uprading Slackware to keeping an Arch Linux running. With Slackware, I have to sit down for an hour, do the upgrade, read the notices that come along with it, maybe see if it will break any of my custom packages. This happes once or twice a year (security upgrades are completely painless as they don't break things). With Arch Linux I need to do that every day. If I don't have time to do it for a month, the system is basically broken beyond recognition...