Slowest rehab ever?

I'm beginning to think I might be overly cautious in my rehab schedule. (Which will not shock anyone who knows me...)

Tris is 100% sound, and we're not worried about rehab-induced re-injury; it's not a soft tissue problem. His hoof has healed over, the bone has sealed, etc. Our only limitation is fitness: muscles, wind, and old-horse joints (he is 18 this year).

So here's our schedule, followed 5 days a week with 1 day completely off for recovery and starting this week, 1 day of a long road hack with hills. We are about to start Week 7.

Week 1: 20 minute walk
Week 2: 30 minute walk
Week 3: 15 minute walk, 5 minute trot, 10 minute walk
Week 4: 20 minute walk, 5 minute trot, 15 minute walk
Week 5: 15 minute walk, 5 minute trot, 10 minute walk, 5 minute trot, 5 minute walk
Week 6: 15 minute walk, 5 minute trot, 10 minute walk, 5 minute trot, 15 minute walk
Week 7: 15 minute walk, 7.5 minute trot, 10 minute walk, 7.5 minute trot, 10 minute walk (Day 6: 60 minute road hack @ walk)
Week 8: 20 minute walk, 7.5 minute trot, 10 minute walk, 7.5 minute trot, 15 minute walk (Day 6: 60 minute road hack @ walk)
Week 9: 15 minute walk, 10 minute trot, 10 minute walk, 10 minute trot, 15 minute walk (Day 6: 60 minute road hack @ walk)
Week 10: 15 minute walk, 10 minute trot, 5 minute walk, 10 minute trot, 5 minute walk, 2-3 minute canter, 10 minute walk (Day 6: 60 minute road hack @ walk)
Week 11: 15 minute walk, 10 minute trot, 5 minute walk,  10 minute trot, 5 minute walk, 5 minute canter, 10 minute walk (Day 6: 60 minute road hack @ walk)
Week 12: 15 minute walk, 10 minute trot, 5 minute walk, 10 minute trot, 5 minute walk, 10 minute canter, 10 minute walk

At Week 12, I'll feel comfortable chucking the more rigid timing and going back to work based on feel. Right now the trots are mostly straight lines, with him in the bridle but not really properly on the bit, more focused on rhythm and softness and rideability than dressage. Last night, we trotted up a small hill, and I'll continue to incorporate that and poles and other strengthening exercises as he feels able. We should finish the second week in August. At about that time we might introduce some hand gallop in the ring. I'll have to do some thinking about a proper gallop set; there isn't really anywhere flat with decent footing for this nearby. All the good fotting is on some sort of an incline, and all the flattish stretches are on hard-packed dirt road, so it will depend on how he feels in hill work at the trot and canter. We'll also take jumping as we see fit; certainly not until this schedule is complete but it may be that we take advantage of the dressage trainer before she goes back to Florida and hold off on jumping until the eventing trainer comes back to clinic in the winter. Then again, I might get too tempted by the jumps in the upper ring before then and pop over a few.

eta: I might also add lessons in at Week 10, once a week, to focus on re-starting the canter right - that's always been our challenge and it would be good to have some help from the beginning.

What do you think? Most pointlessly over-cautious and slow rehab in history, or a sensible, gradual plan?