Hopefully most of the time. :-)

Seriously I find that my average function is about 10 lines. Some are shorter - a lot shorter. A few are much longer. But that seems to be an average for me.

Here is a list of reasons from chapter 5 of Code Complete to think about. I won't copy explanations, just the reasons:

1. Reducing complexity
2. Avoiding duplicate code
3. Limiting effects of changes
4. Hiding sequences
5. Improving performance (optimize later)
6. Making central points of control
7. Hiding data structures
8. Hiding global data
9. Hiding pointer operations
10. Promoting code reuse
11. Planning for a family of programs
12. Making a section of code reusable
13. Improving portability
14. Isolating complex operations
15. Isolating use of non-standard language functions
16. Simplifying complicated boolean tests

I have found that all of these benefits still hold in Perl. Well performance is usually hit a little, but you are left in a position to optimize where it counts later. And you shouldn't have non-standard language functions. But in practice I have noticed portability issues from time to time.

So while that list doesn't hold perfectly for Perl, it is still generally on target.

Note that in particular comments explaining what you intended at one point are not a good substitute for clear code. Should you change the code later, the comments will often remain to confuse you. Also deeply nested loops may not take many lines, but they make it much harder to separate the forest from the trees.