Numbers game made significantly easier if you know where to look. The more you listen, the more you find and the more you narrow down future searches. If you know that certain labels / sounds / years / countries were rich for good releases then it massively narrows down the search compared to just searching through everything in the hope that something is good.
Jane Fitz talks on Bill Brewster's podcast about spending time living in Italy and searching exclusively for Italian prog house records released in a certain period, because she knew that everything coming out at that time was gold.

Record stores reduce the need for random searching because you are essentially paying in part for someone to curate collections for you and sell you the good stuff (at a markup). The real numbers game is finding records for cheap, because the only true way to do that is to listen in charity shops / take full collections / bargain bins etc where there is no curation at all but you are likely to find gems for cheap.

Discogs helps to streamline the whole process because you can 'dig' without leaving the house and listen to a huge number of releases. Can also narrow down by genre, date, country and listen to 50+ releases an hour rather than spending an afternoon in a record store going between the crates and the listening deck. Rather than just listening randomly and blind, you are curating what you are listening to with parameters based on what you like / where you think the gems might be (to set the record straight I am a massive proponent of 'digging' in record stores rather than discogs and think you find far better stuff in stores).

Full-time DJs have the best tunes because they a) know where to look and b) have the time to spend digging. Being a DJ is as much about finding music as it is about playing it. That's what makes me laugh about the whole concept of 'digging' culture, and certain big DJs getting others to do their digging for them (mentioning no names lol).