SubID tracking vs separate tracking IDs: SubIDs scale, tags don't

SubID tracking vs separate tracking IDs: SubIDs scale, tags don't
Amazon caps you at 100 tracking IDs per account but allows unlimited SubIDs (the &ascsubtag= parameter) inside one tag.
— Tracking IDs: clean dashboard separation, but you hit the 100 ceiling fast on a large site
— SubIDs: unlimited granularity (page, position, A/B variant), but you must parse the report export yourself — the dashboard won't split them
On a 600-page site we mapped EPC per template via SubIDs and found the sidebar widget earned $0.04 vs $0.31 for in-paragraph links (n=44,000 clicks).
So what: use tracking IDs for big buckets (site, newsletter). Use SubIDs for everything granular. Don't waste your 100-ID budget on per-page splits.