No mistake since 8 months? Seems it had to be time that somebody messes up big time.
Did my worst mistake ever yesterday. I found an arb (about 3%) on a nhl game over/under 6,5 trough a free service, which I use quite often. So I had no doubts and wanted to be quick. I got 250€ on one site and 520€ on the other side. I checked again some minutes later and saw I bet on O6,5 in regular time and U6,5 including overtime. I wanted to compensate the mistake with other bookies, but were limited everywhere with decent odds, so I thought I let things slide. Of course the game was 3-3 after regular time and went into overtime. End result: 4-3 after penalty and -770€. Thats probably more than I make with arbs the whole month. Hopefully I am never ever that unconcentrated again in my career.