Thanks, that helped me a lot!

After some testing I have written/adapted portfolio trading code as follows:
- 1 mean reverting strategy (as used in the workshop examples with further optimization of the fixed parameters): 5 parameters to be optimized
- 1 trend following strategy (likewise as above): 3 parameters to be optimized
- cycling through all assets for which historical data is delivered by jcl, so that each strategy is applied to each asset (btw: I use 240 minutes time frame for MR strategy and 60 minutes for TF)
- optimization done with MODE=RISKLIMIT
- testing done with MODE=OPTIMIZED+RISKLIMIT+MARGINLIMIT+TICKS
- Walk forward optimization with 8 steps

Test results are as follows:
- Using 4x oversampling: 197%, sharpe ratio 1.57
- Using no oversampling: 267%, sharpe ratio 1.79
- In both results I get nice upward stepping equity curves

What puzzles me is the fact that I get better results both in terms of risk and profit using no oversampling. On top of that with 4x oversampling it takes forever to calculate [one day of training vs ca 1.5h using no oversampling on my machine]. In addition it threw an error message at the end of the optimization (Too many trades) which I ignored several times to finish the test and to get the last fac and nfac files.

What makes me a bit uncomfortable about going live with this strategy is the fact that walk forward analysis is most profitable with 8 steps, but if I only vary by +/- 1 steps the results get far worse.

Is this a sign of an unstable/over optimized strategy or can I still assume that the system will be profitable during live trading?

Another question concerning live implementation of this system:

Using 8 steps for walk forward optimization I assume that the data set (minus Look back period) is divided by 8 to perform the walk forward test of each data set slice.

Does this mean in live trading I have to stop after the same (slice) period to make a new optimization or is there a way to automate this process (so that I can leave the strategy alone and it will automatically reoptimize itself at the right moment)?

Thanks for your input and happy to get further advice on how to improve my approach (as well as hints on how to get in the area of Z1 performance figures => of course without revealing too many secrets about it).

Kind regards
Chris