I'm the one who raised questions about the Townies. However I think I meant "cruisers" more than townies per se. I always get those confused because I'm enamoured with all those beautiful Electra bikes!!!

This being said, what I meant was that I'm not sure "comfort" bike are a good choice to do "power" workouts. This has nothing to do with distance, I'm sure you can ride for days on any bike as long as it's a good fit. However if the goal is to, for example, practice powering up hills, or doing fast intervals at really high cadence,

This is based on nothing but intuition, and I would have liked someone who knows a lot more than me about bikes to respond to this. I'm just thinking that these bikes are meant for "comfort", not for "speed", and that they are fit accordingly on their users. But honestly don't make too much of this. As Knot says, if it works for you, don't worry about it. If you start having pains, check your fit.