Currently, it’s impossible to practice flash cards in random order. It’s good if there is a option to do so.
The reason rems are clustered
I believe people often make many rems on the same topic, hence, flash cards for the same topic tend to be clustered. This can’t be prevented by turning off rem clusters options in the “Ordering” section in the settings.
The solution
I guess the scheduler algorithm don’t need to be changed if there is a option that cards in the queue show up randomly regardless of the order (their target date?).