As always you can say: it depends. It's more a question of naming and defining the task of a method. Every method should do one (not more) well defined task and should do them completely. The name of the method should indicate the task. If your method is named DoAandB() it may be better to have separate methods DoA() and DoB(). If you need methods like setupTask, executeTask, FinishTask, it may be useful to combine them.
Some points that indicate, that a merge of different methods may be useful:
- A method cannot be used alone, without the use of other methods.
- You have to be careful to call some dependent methods in the right order.
Some points that indicate, that a splitup of the method could be useful:
- Some lines of the existing method have clear independent task.
- Unit-testing of the big method gets problematic. If tests are easier to write for independent methods, then split the big method up.
As an explanation to the unit-test-argument: I wrote a method, that did some things including IO. The IO-part was very hard to test, so I thought about it. I came to the conclusion, that my method did 5 logical and independent steps, and only one of them involved the IO. So I split up my method into 5 smaller ones, four of them were easy to test.
