The following chart is an example of one of my systems that had been a good earner previous to this year. I will continue to update them when I get the relevant data from the BfSp history site.
1 point stake / 100 point bank / Lay limit 4.00
If only I had started after Cheltenham.
Though my approach is ratings and filters combined with methodology, I believe this year's weather made my May and June less profitable. I adjusted for July and August but September, I felt the whole time like I was driving 'my car' on the verge of going off the road.
The factor is sometimes obvious. An example; a friend of mine built an algorithm for determining total runs in a baseball game. It did okay. What made it a winner? When he found a site that gave wind direction/speed and barometers for every ball park live.
I also think you should stick with it. It didn't kill your 100 pts. A system is sometimes like a business where you have to look at the entire year rather than each month.
That said, I hope you have a fantastic Christmas!