Options, options, options
Just use a good default value, instead of lots of options.
Far too often a dispute is settled by introducing an option.
"I want it to be ten, no I want it to be twenty. Okay, lets add a feature where one can choose how many."
That, off course is a bad thing. Drupal, or many OSS has no interface workgroup, nor does it have a marketing dept, to tell them to simply take 12, or seven. Or whatever number the users in general prefer. And then leave it with that. Open Source software has a lot of user feedback, yet no real data.
Configuration panels are there for disciples, not the geeks. So don't confront them with options that they would never set. Simply because as soon as one knows what the option is for, one would already have reached such a high level of experience with this operating system that one would be able to simply alter the desired files directly. So keep it simple and stupid.
In other words: do not bother too much about the exact number, nor about whether or not people are going to settle with the predefined options you give. Just choose what you think is the best, and leave it with that. Feedback will then allow you to finetune these predefined settings.