G'Day Shoto, without a doubt (take a tip) it is definitely the losing run that will kill it.
taking the opportunity to reminis here but you may get something out of it. I operated a cover to win system in England successfully for over 2 years and thought I was set for life, but of course the inevitable happened "a horror run" I lost all I'd won plus the bank plus more besides.
The staking plan was sound, aiming to win a set amount per race + the previous losses, betting race to race at the principle meeting , following on from day to day. The in built saftey brake was to count any runner under 3/1 AS 3/1, (the particular method of selection included Fav's but also all prices up to 33/1)eg.
Race, SP. Aim. Stake. Res. W/L. To recover
1 5/1 $10 $2 L -$2 $12
2 1/1 $22 $8 W +$8 $14
3 4/1 $24 $6 L -$6 $30
4 8/1 $40 $5 W +$40 nil
5 2/1 $10 $4 L etc etc

This was the basic plan but I refined it later to spread the risk much more and built in reserve banks etc. all of which I can outline if there's any interest?

In my case the selection method fell in a heap, and I never recovered. Though I've thought afterwards that I should have had 2 or 3 banks available, with a maximum bank to lose on any progression, so that in the event of a horror run, you would lose 1 bank but not get cleaned out (hopefully)