TechWhirl (TECHWR-L) is a resource for technical writing and technical communications professionals of all experience levels and in all industries to share their experiences and acquire information.
For two decades, technical communicators have turned to TechWhirl to ask and answer questions about the always-changing world of technical communications, such as tools, skills, career paths, methodologies, and emerging industries. The TechWhirl Archives and magazine, created for, by and about technical writers, offer a wealth of knowledge to everyone with an interest in any aspect of technical communications.
Here's another reason for third-party manuals, and it's perfectly legit.
My mother did temp work a couple of years ago. She was trained on several
different WP packages, but didn't have them all at home. She bought several
third-party books, as home study guides.
When on an assignment, she'd take the relevant book with her, so that she'd
have a familiar resource available while on the job. (Employers would
sometimes ask why, if she was an "expert," she had to bring a book. As we
all know, different jobs mean different emphasis on features, so a temp
has got to look things up from time to time.)
rlippinc -at- bev -dot- etn -dot- com