[helene_t]

Sometimes I have the feeling that I can run into a "wave" of the field in the MR being either very favorable or very unfavorable.

This might be a spurious "finding", but sometimes when looking at how the other tables looked like, I get an idea why it might actually be a real trend: the field will be small (only 1-3 comparisons so far), and the other tables will often have two or three robots with the human(s) being N (or NS). Now if this human is either a very bad player or doesn't take the game seriously, it will be an advantage to be NS at our table since the other NS often get bad results. The same could happen with four humans of course, although it would probably be coincidence if EW were much better than NS at all tables. But such a coincidence could easily happen if there are only a couple of other tables and we are generally compared to the same other tables for some time.

One way of eliminating this problem would be to, whenever we need a board with, say, S as dealer and NS vul, allow us to alternatively get a board with, say, E as dealer and EW vul and then turn it 90 degrees. That would destroy such a "wave" of biased fields and have the added advantage that there would be more boards suitable for our table so it would less often be necessary to create new boards while some boards are still unsaturated.