I wish I knew where that balance point is. It's more than likely a moving target. It probably differs for different people and conditions. I don't think one day off your feet would cause any appreciable degradation of the foot strength. I do believe that if you took a month and stayed off of your feet, you would lose enough arch integrity to increase the proportion of tendon stress at the heel attachment point. This I suspect would be due to the lack of load distribution from a strong arch. How long have you had symptoms? Have you tried orthotics or tape? I'm sure that what worked for me isn't going to help everyone, but I'm a firm believer in arch support as the key factor. Keep at it and take in all of the advise from fine folks on this board. Hopefully you can get out of this mess without a new horror story!