How to avoid creating huge classes

Use a tool like Resharper and the Extract Method command.

I guess it depends on your internal processes as much as anything.

In my company, we practise peer review, and all code that gets comitted must be 'buddied in' by another developer, who you have to explain your code to.

Time constraints are one thing, but if I review code that has heinously long classes, then I won't agree to the check-in.

It's hard to get used to at first, but at the end of the day, it's better for everyone.

Also, having a senior developer who is a champion for good class design, and is willing and able to give examples, helps tremendously.

Finally, we often do a coding 'show and tell' session where we get to show off our work to our peers, it behooves us not to do this with ugly code!

Long classes is one bad code smell of many possible.

Remedying overly large classes by creating lots of small ones may create its own problems. New engineers on your project may find it difficult to follow the flow of the code to work out what happens where. One artifact of this problem can be very tall call stacks, execution nesting through many small classes.