No, it means an extra day of cost.If that were true then surely an extra day means more money?
The vast majority of the time, people won't turn up to watch (in all liklihood) just a few overs of a game, that was only confirmed 12hours beforehand. On a weekday.
As it is, they sell 5th day tickets for about £20, and recently started giving them away to get people through the door when there's a tight finish.
Given most of their money comes from broadcast deals, from Sky's perspective they're getting the same number of matches but an extra day of people hanging around a ground to pay for. And a screwed up schedule when they have to allow for an extra day of play that probably won't happen.