Originally I had a vision that you would give them 5 minutes in class to start and the rest would be homework, or something to be completed if their math, or other class work was done. If they have a target number of words, that can be completed at any time. You can still “mark it” the next day by having students exchange papers. That will still work.
However, most teachers seem to have found this such a productive activity, that they have incorporated it into their regular practice.