I am working on a site redesign which is moving from one CMS system to another, with thousands of old pages being moved to a new structure. Some pages have a 1-to-1 mapping from old to new, but thousands of other pages have no exact equivalent, just a general topic landing page.
I'm being asked to massively redirect groups of old pages to three new landing pages (1300 redirects, 500 redirects, and 300 respectively), and then everything else (1200 more redirects) to the home page, but something about this doesn't feel quite right. I know Google specifically says not to redirect old pages to the home page, but I'm having trouble finding any information about landing pages.
To give an example, let's say I sell computers and have 1300 pages with various content such as marketing information about specific components, others talking about manufacturer rebates, some showing comparisons between different parts, some talking about current sales, etc. In other words, a wide variety of pages on the topic. There are no equivalent pages in the redesigned site, but there is a new landing page for computers like
http://example.com/computers.html with a little bit of content.
Is 301 redirecting all 1300 old pages to this new landing page the right thing to do? What's the best practice for SEO in this case? Do you have any authoritative sources that talk about this scenario?