Something doesn't sound right here.
I think 'breaking in' shoes is really a throw back to the days of leather shoes that had to be softened through use. These days IMHO, it's more a case of your feet getting used to the shoes.
My Salomon boots were great from day one. Like bedroom slippers.
I'm sure those more experienced will offer great advice, but here's my 2 cents worth.
- Make sure the shoes/boots are professionally sized/fitted.
- Ensure you are wearing your walking socks at the time. 2 pairs. A thin inner (synthetic) and a thick outer (wool).
- Make sure the shoes are half to a full size bigger than you would normally wear. This allows for the double socks, plus swelling.
- Watch some youtube videos on lacing shoes/boots for walking. Different techniques might help.
- When trial walking. make sure you Vaseline your feet, around/between the toes and heels in particular. Lots of it.
- Consider going to a Physio. A good one. Get them to video you walking, to check your gait. They may suggest Orthotics. Or maybe even an issue with your gait, that can be rectified with exercises. My wife Pat was at our Physio today. We found her Plantar Faciitis is caused by her gait, due to certain muscles not being strong enough!
Can't think of anything else at this stage
But consider this.....
You have tried 6 pairs of shoes/boots, all with the same result.
The common denominator? You and Your feet!
Maybe it's not the shoes? Get to a good Physio
Re the 'burning'. Are your feet just 'hot' or
painful? All feet get hot. Friction is going to cause heat and discomfort. Maybe the shoes are too big and your feet are sliding around?