Actually, nothing stops the CEO from saying that it's no more than 10. The CEO, under paragraph 16(d) of the Canada Elections Act, has the power to make instructions to election officers. If I may add, the Chief Electoral Officer has already announced that for the 2019 general election he wouldn't be implementing the model of voting at any table, because he just doesn't have time to implement that.
Let's project ourselves into the future. At the following general election, if the model of voting at any table is allowed, the services to voters at the polling stations should be more efficient, and there should be much less of a wait at the table where you vote, because you will be able to go to the next available election officer. In that context, in very densely populated areas, it may be possible to administer a polling station with more than 10 polling divisions, if the flow of electors is very efficient.