I was trying to run a Express MaxDiff over 35 items, as we are asking the users to go through two exercises (one asking most/least unique, the other one most/least attractive). So we set up the design in such way that every respondent will evaluate 20 items of those 35, showing 5 items per task and going through the tasks 12 times.
So I created both files and combined them but my final design lacks all of the principles, starting from frequency balance, as there are shown just 593 times vs other shown 637 times. We don't have either position balance nor orthogonality.
Is this common, how will this affect the results?