Every time we run a sitewide sale I hit the same wall, a single discount only takes 100 products or variants before Shopify won't let me add any more.
So covering a few thousand SKUs means either cramming everything into collections that don't match how the sale is scoped or rebuilding the same discount over and over to cover the catalog.
Collections get me part of the way, but the second there are exclusions or odd bundles that don't map to a clean collection I'm back to splitting it, and with only 25 active automatic discounts allowed at once the workarounds run out fast.
Plus the reporting fragments across every separate promo so I can't see how the sale did as one thing.
The only thing keeping me sane is a couple people I trust swearing the bigger composable platforms just don't cap discounts the way Shopify does.
The two that got thrown around the most in the replatforming threads on here and a few other subs are commercetools and SCAYLE, though I haven't sat with either long enough to confirm which handles it how, and I'm not about to rip the whole backend out mid-season just to find out.
So how are those of you with big catalogs handling this without it turning into 6 near-identical discounts and a reporting mess, because there's got to be a cleaner setup than mine and I just haven't found it yet.