Would like to understand if it's worth updating & redirecting old pages to new structure. I'm seeing significant decline in traffic on the old pages, while traffic on the new ones continue to grow.

Its a move that happened a while back already where 80% of old pages have structure like: example.com/node/123/music/top-conerts-in-2025 and the rest of the new 20% pages have structure like: example.com/music/bass-music-players (new URL structure in new page design). So, 2 different URLs formats.

If a site moves to a new URL structure without redirecting old URLs (old articles remain indexed under the legacy structure, new content uses a cleaner format), could this split in URL patterns affect overall site rankings? Do you recommend to redirect old URLs to new format for consistency?