It seems from what I'm reading that much of the pheasant available is from game farms and / or hatcheries. So sometimes the recipes in various books might be assuming a yearlling, or at least a young bird, and you should be prepared to have to cook for a while longer than they say to get the bird tender. I'd guess braising for 60 mins is a minimum, 90 might be average, and you might have to cook the thing for two hours to get some birds tender.

Hanging the bird for a week will probably also make it more tender. This is getting into food hygiene territory though, and I'm no expert here. So please don't take that as a recommendation - rather it's a statement of what cookbook authors might be working with when they write up their recipes.