FSRS 5: Effect of Presets on Retention

[Keks]

@Expertium

I suggest you to try combining presets: put two decks that were previously under two different presets under the same preset, then Optimize, then Evaluate. If the RMSE after combining them is lower than the average of RMSE before, keep one preset.
Example:
Before: preset A, RMSE=5%, preset B, RMSE=6%, average=5.5% (for simplicity, assume equal number of reviews in both)
After: preset A+B, RMSE=4%

Apparently, the method is not working.
Preset 1:
Log loss: 0.214, RMSE(bins): 4.03%. 10,414 reviews
Preset 2:
Log loss: 0.4262, RMSE(bins): 4.59% 6,423 reviews

Combined preset:
Log loss: 0.2840, RMSE(bins): 3.41%

I separate the presets but leave them the FSRS parameters of the combined one:
Log loss: 0.220, RMSE(bins): 4.01%
Log loss: 0.4314 RMSE(bins): 5.23%.

It would be interesting to look at presets with closer Logloss and RMSE.