It's best to race at night in your location/time zone and avoid peak times if you ever want to have a chance at winning or finishing on the podium. Unless you're an elite alien phenom that can win outright, other mere mortals with lesser talent don't have a chance.

Another benefit is you can avoid most of the casual people who are wild and crazy wreckers. The vast majority of those will probably race during peak hours.

Some may enjoy racing in a top split full of high iRating aliens for a proper challenge and that's fine. It's no guarantee racing during night hours will always have weaker/soft competition as some aliens race during those times. But the key factor is there will be less of them and that can only help pad your stats and net better finishing results.