what's your process for aing 301 redirect work?

Leave them in place for good, or at least a year - that's Google's own minimum, and people keep old bookmarks and links for much longer than that. Somebody deleting the redirect rules in a tidy-up six months later is how a site loses its rankings twice.

Mine goes: export every old URL first, from a crawl plus Search Console plus analytics, because each source catches pages the others miss. Map each one to the closest matching new page - not everything to the homepage, that gets treated like a soft 404. Set the 301s at server level or through the CMS. Then update your internal links to point straight at the new URLs so you are not relying on the redirect at all. Last step is a fresh crawl looking for chains and loops. Chains are what catch people out: old to older to new, every hop is another chance for something to break. Keep it to one hop.