I guess it depends on your stress tolerance level. When I was younger and just starting here on FT, I connected A to F and F to A without issues, even on tight connections, and even on HP metal to US metal (and the reverse).

Right now, however, I'd prefer to have a bit of a cushion, especially before a TA flight. While the lounges at PHL aren't nearly like the Envoy lounge used to be (), they are still decent enough to spend a little time between flights. Plus if you don't have much carry on, you can walk around and explore the airport a bit...or eat some Chickie & Pete's