Is time or intensity more important after running injury?

I was just on a call with a trail runner who is recovering from both a sesamoid bone injury as well as a peroneal tendon injury. Right now she is focusing on working toward running on long technical trail runs in the mountains. To that end she is doing a lot of different forms of activity to supplement her running fitness.   During our call, she asked a great question... "Should I be adding a lot more time or a lot more intensity to rebuild her running fitness." Which is more important to increase first, after you have had a running injury, time or intensity?  Well, that is a great question and that is what we're talking about today on the Doc On The Run Podcast.