If you can do it for an hour at 65% you can do it every day.
If you want to.
Check out walking with poles/nordic walking.
I just started about a week ago and the added upper body work can be more significant than I expected.
Also gives you something to keep varmints at more than arms length.
Weighted vest walking is great. It will basically be up to how you feel when deciding frequency. My rule of thumb is muscle aches are fine, joint/ligament pain bad. Make sure your posture is good while walking, don't let your shouldersand back 'sink' in.
Keep chest up, shoulders back and you should be fine.
good luck with the vest and keep us updated on your progress.
These days I follow a 3 day cycle of activity that gets me outdoors every morning. Day 1, I jog. Day 2, I walk with a weighted vest and Exerstrider poles. Day 3, I walk with "HeavyHand" weights, pumping vigorously and throwing in dips and "double ski poling" movements.
I have no science to back up that this approach is especially good. I wear a heart monitor and I follow Phil Maffetone's guidelines about HR, which, I believe, parallel Mark's warnings against "chronic cardio." I love the fresh air, breathing deeply and the constantly changing weather, as well as the variety my different approaches for covering ground offers.
I mention all this just to offer food for thought as you explore weighted vest walking.
Enjoy your walks ! :-)