Sharing Course Material With Other Lecturers
Whether to share-or-not (assuming that you yourself, not your university, own the rights to what you've created) is strongly a matter of personal preference... I don't see a universal mandate.
Many years ago, I did pay careful attention to copyright control, and so on, but eventually I got the impression that it was simply not the case that people were clamoring to get their hands on stuff I'd written. :)
So, for some years now, I've put everything on-line with a Creative Commons license, and whenever anyone is polite enough to ask permission for use, I give it, without any negotiations. In fact, if one of my goals were to maximize the impact I have on ... for example, graduate curriculum in mathematics... unrestricted dissemination seems the obvious choice. True, I may not &quot;get all the credit I deserve&quot;, but I already have &quot;enough credit&quot; to survive, so that'd not be a tragedy.
A situation where one should be more careful is when one's institution attempts to use-and-discard people who develop course material. In such cases, &quot;getting credit&quot; probably matters much more. Luckily, till now anyway, that kind of thing has not been toooooo much of an issue at my university, although arising sporadically over the years. (I'm not optimistic about the future...)
In summary: if you don't want to share the fruits of your labors, don't. You may change your mind later, and that's fine, too.