@David-Healey Yeah, I don't ever see myself doing that amount of automation. It feels too forced and contrived to me.
I've tried it before with different products (non-music related) and I ended up spending more time endlessly tweaking campaigns than actually making the product better.
My strategy over the last 3 years has been quite sparse:
Products: one launch email with a time-limited discount code, then one reminder email 2-3 days before the code ends.
Marketing: maximum one email per month with a product-specific discount code, only sent to those that don't own the product.
On top of that I've sent out a couple of cross-sell discount codes ("Since you own Product X you might like 20% off Product Y") and a DAW survey.
I do have it on my list to send out a post-purchase email, something like "Hope you enjoy Product X, here's a 20% discount code for your next purchase". It's easy to set up in Gumroad, just haven't got around to it yet. It would be very easy to measure the performance too. That's more like the kind of thing you posted above.
EDIT: just read through this again and I think I'm actually just very lazy! 
