The problem with full Kelly is that it requires precise knowledge of your edge, which nobody has. A bettor who estimates 10% edge when the real edge is 5% is risking twice what Kelly would recommend. The result is higher variance and larger drawdowns than the growth-maximizing strategy. Full Kelly also produces swings that are psychologically unsustainable for most people.
Half Kelly or quarter Kelly is the practical answer. Half Kelly cuts the growth rate by 25% but reduces variance by roughly 75%. Quarter Kelly is even more conservative. The growth sacrifice is real but manageable. The variance reduction is enormous. Most professional bettors use some fraction of Kelly rather than full Kelly.
Flat staking, where you bet the same amount on every pick regardless of edge, is the most common approach for recreational bettors. It is simple and easy to follow. It also ignores the mathematical reality that a 5% edge and a 1% edge should not receive the same investment. Flat staking works if your goal is entertainment. It is suboptimal if your goal is long-term growth.
The most destructive habit is increasing bet size after losses. This is the gambler's fallacy: the belief that a losing streak makes the next bet more likely to win. It does not. The odds are the same regardless of your recent results. Chasing losses with larger bets is the fastest path to ruin. The discipline to maintain consistent sizing, adjusted only by genuine edge, is the hardest and most important skill in sports betting.