Now that sales are picking up, we don't know how many more weekends staff will be asked to work, or how many fewer vacation days they will be allowed.
Now that sales are picking up, we don't know how many more weekends staff will be asked to work, or how many less vacation days they will be allowed.
Now that sales are picking up, we don't know how many more weekends staff will be asked to work, or how many fewer vacation days they will be allowed.
Now that sales are picking up, we don't know how many more weekends staff will be asked to work, or how many less vacation days they will be allowed.
If we are talking about something we can count, something for which we would ask "how many?" instead of "how much?", then we need to use "fewer."