Sports betting
What is a betting system?
A betting system is a rule for how much to stake next, usually based on what just happened. Martingale doubles after a loss, Fibonacci steps a sequence, D'Alembert adds a unit.
None of them changes the price you are getting, which means none of them changes what the bet is worth. They redistribute your losses into a different shape.
What a staking pattern actually does
Martingale converts many small wins into one enormous loss. It works right up until the table limit or your balance arrives, and both of those are closer than the sequence assumes.
Eight losses in a row on an even-money bet happens roughly once in every two hundred and fifty sequences. Start at C$5 and the ninth stake is C$1,280 to win back the five dollars you began with.
The gambler's fallacy underneath
Every one of these systems leans on the idea that a run is due to end. A roulette wheel has no memory, a random number generator has no memory, and a coin does not know it landed on heads five times.
Sports is slightly different because outcomes are not independent, but not in the way the system assumes. A team on a losing run may genuinely be worse now, which argues for backing them less, not more.
The one honest version
Flat staking is a system and it is the only one worth using. Same unit, every bet, regardless of the last result.
It will not manufacture an edge. It will let you see whether you have one, which is the most a staking rule can honestly do.