Here is a formula for working out what losing sequences you can expect:

Bets = 1/(1-SR)^n

where n number of losers in a row
Bets = no. bets before you could expect such a sequence
SR = strike rate as a decimal.

eg. favs

SR = 0.3 (30%)
n=10 (10 losers in a row)

1/(1-0.3)^10 = 35

so you could expect ten favs to lose in a row once every 35 bets.

This scared the crap out of me the first time I saw it!

This seemed a bit "off" to me initially but if you consider it this way it makes more sense.

If 11 lose in a row that is 2 times ten losses in a row. So if you go 70 bets and have one losing sequence of 11, you have actually had two losing sequences of 10 which averages out to 1/35.

note : you can expect 11 losers in a row once every 51 bets (@30%SR).