Meant to comment earlier: glad to see you got a cassette player! (Having played this series since the weekend of the original Dreamcast release, I was shocked to win a player on the first in-game day of the PS4 remaster.)
IIRC: though these factors affect both games, gambling success in S1 is more dependent on factors such as date, time, and even weather. For instance, if you gamble around Christmas and New Years, you're much more likely to win in raffles and collect free cans from soda machines (which, of course, increase your chances of winning, esp. at the harbor).
If memory serves, there's a thread in which S1 probabilities of winning were calculated with respect to those factors; perhaps search for posts from users Spaghetti and/or DigitalDuck and see what you can find.