Common wisdom says you should buy vehicle that will meet your needs 90% of the time, and rent whatever you need for the rest. Since my car spends 90% of its time at an airport garage or driving to an airport, I've got a small car that's comfortable for me and one other (and will seat 4 in a pinch).
So it is with automation tasks. I will commonly build out install packages for the 90% use case: SQL Server installation is a common task, which, while it must be executed correctly and ideally the same way every time, is not terribly interesting once you've done the initial configuration. There are a dozen other middleware components, a dozen agents, a dozen common configurations: changing the name of the built-in Administrator account, for example. While all of these are "common" tasks, I often end up talking to people trying to automate the most complex configurations in their environment, or seeking tools to address 100% of the tasks at their hands.
I share their interest: I rarely want to bother with the easier tasks in a given environment:it's boring, and once you've installed Oracle 11g a couple of times, there's really not that much that's interesting in it, unless you're trying to do something completely different (like stand up a 3-node super-HA RAC). All of that said, I've been noticing lately that it's far easier for us to set aside the basic work that needs to be done, the first 80-90% of automation tasks, like setting up the various patching, security, regulatory or build compliance audits, or building provisioning or software deployment packages.
Instead we tend to focus on whether that last remediation instruction is exactly correct, on whether one condition in particular works correctly on 100% of the systems. Unfortunately, that last 10% seems to cost as much (time, money, resources) as the first 90%. A customer I know of has a metric on their software installs: every time one of their senior resources doesn't have to spend an hour staring at billboards while a given software package installs, they add $40 to the automation bucket, and at the end of the year they total it up.
Now, it's not fun or exciting to setup and maintain the "first 90%" jobs, but they get the job done, and you'd be surprised how much they'll save your organization over a year. If you want to know exactly how much, just setup a quick report to measure the number of runs over the course of a year. Then you'll know how much time you freed up to work on the "more interesting" tasks.