>Personal preference,
>
>My take: One class per classlib means it isn't a lib. It's a class. Why even have the classlib at this point? A class should have one purpose and one purpose only. This is called out in the Single Responsibility Principle (read about it at http://www.dotnetcurry.com/software-gardening/1148/solid-single-responsibility-principle) A classlib should hold *related* classes. For example, a classlib with stuff for a form should have nothing but stuff for a form. Nothing for reports.

Only that purpose is a field as wide as one likes it. Is dealing with strings a single purpose or is LTRIM one?

You are very fond of such principles and rules, aren't you? Real world (aka: the hazy border of the screen) is different.