I have changed the URL for a large portion of my website (150,000+ URLs) to follow a SEO-friendly structure like all lower-case and hyphenated URLs (earlier they were capitalized at places and had whitespaces (%20).The content remains the same on the both URLs and there was no migration from HTTP to HTTPS. I have ensured proper 301 redirections from all the old URLs to the corresponding new URLs. It was all done in one shot.I read a lot before implementing it way back in mid-August and found people supporting this approach of page-by-page redirect. Like Matt Cutts supporting such large scale re-directions.I know there is a slight drop in link juice on doing a 301. I raise this concern as I have seen a gradual decrease in organic traffic  since the start of September.Can the large-scale redirection lead to such drop in organic traffic?Other changes that I did around the same time.Introduction of rel tags - canonicals,next/prev. I audited my implementation and it is correct.Then earlier I used to dump all my URLs in the sitemap then I restricted them to only the top level pages. Before the change I had 3,00,000+ URLs in sitemap and after change around 30,000 URLs.
Is large scale of 301 redirects for URL change harmful for SEO?
seo;redirects;url;301 redirect;traffic