Very briefly:

I reckon this depends on the number of bets wagered and the way they are staked - so time - one week, one month, six months is not the main factor.

A percentage of a wagering bank that is lost is more to the point - as is the way the money has been lost.

For example if in your series of bets you've had 20 photos and lost 19 of them by a head or less you know that's real bad luck. That's vastly different to a similar 20 bets where you lost 19 of them with the horses all finishing well down the track.