Layer System and Injury Prevention

CT, first of all thankyou for all of the great info on the layer system so far! I am currently using the Ramp/densit/carries protocol and loving it!

However, in the past I have had a couple of injuries which have set me back (shoulder rotator tear and biceps tendonitis).

Whilst I have healed both of these a while ago now, I am a little paranoid about them reoccuring.

So I have been adding in rotator work after pressing workouts (but not much since I thought the overhead carries would pretty much take care of this)

and also I have been adding in bicep work - slow eccentric DB curls to stengthenthe biceps tendon, performed after pulling workouts. (3-4 sets of 10)

Do you think this is neccessary for the layr system?
Would they effect results negativley?
Would it be better to do these on a rest day?
Do you persoanlly do any prehab work in your training?

As always it would be interesting to know your view on prehab work and where it fits into the layers, if anywhere!

Many thanks

I should also say it was Distal biceps tendonitis, and this is the one I am most paranoid about reoccuring. thanks