There is no definite answer to how many brackets you should fill out to give you the best chance of winning a March Madness contest as it ultimately depends on various factors such as your level of expertise in college basketball, the size of the contest, and the number of participants.
Generally speaking, filling out more brackets does increase your chances of picking the winning teams, but it also increases the chances of making more incorrect picks. Filling out too many brackets may also not be cost-effective as some contests require an entry fee for each bracket.
A common strategy is to fill out multiple brackets but limit the number based on your level of expertise and the size of the contest. In smaller contests with a few hundred participants, one or two brackets may be sufficient. In larger contests with thousands of participants, filling out multiple brackets (such as three to five) may increase your chances of winning while still keeping the cost reasonable.
Ultimately, the best strategy is to do your research, make informed picks, and fill out as many brackets as you feel comfortable with and can afford. There are many sites that offer free picks but in the end the decision is yours to make.
Licensed and regulated USA sportsbooks are still trying to figure out the best way to have real money March Madness bracket contests. This is all new territory for the industry.
You can find many free contests online from major media centers like CBS or ESPN. Chances are your workplace probably has at least one every year as well.