I used to be a firm believer in the necessity to keep it between 80 and 100, but after spending some time riding brevets with guys on fixed gears... seeing them range from 20 to 200, I don't know anymore. They seem to handle it without injury. But to the OP's question, no I don't exactly do that. For a more intense workout I go faster, indirectly using a bigger gear as needed to keep the cadence where I like. To each his own.