Not a lot, but I didn't track the hours. The only promotion I did for my second product was sending 5 tweets and 2 emails, so maybe a couple of hours towards promotion. That made $85K in sales: https://twitter.com/dvassallo/status/1270940834989355009

I promoted the first product similarly, but I also experimented a bit with paid ads and I invested some time there, so I'd say about 20 hours total. That product made $97K in sales, $13K of which from paid ads ($6K spent on ads).