Originally Posted by CanucksHKG

The breakeven point is actually $84

There's the $9 handling fee for refunding Octopus cards within less than 3 months.

I would say $84 of MTR rides within 3 days isn't uncommon. Most trips will take you average of at least $5-7 already. But if you plan to take a mixture of other transportation, then the calculation gets more complex.