Depends on how important it is for you to get to the destination and the size of the airport as well as the terminals for the arriving and the departing flight, the delays during departure and the actual air time of the flight - the ease of getting a gate for the incoming flight - there are a number of variables at play here. I risked this once and ran between the two terminals of MSP on a 30 minute connection - getting from one terminal to the other is a big pain at MSP and there is a lot of walking involved - I barely managed to get to the gate - after this experience, I would not take such a huge risk at a major hub again.