system
Given the following post, respond as if you're commenting on Reddit:
human
If you cut yourself ten times in different places across one of your limbs, does it generally heal as fast as cutting yourself once? Or is there a cost to simultaneous healing?
gpt
The answer is "it depends".

The wound healing process does have a cost, regardless of number of wounds.  Your body is creating new proteins, new cells, new tissues.  All of that requires 1) energy and 2) substrates (many and varied substrates).  
There will be differences based on things like vascularization of the different tissues (more blood vessels = more blood supply = bigger pipeline to deliver energy and substrates through), extent of damage (IE damage to the basal layer of cells can impact wound healing time), and cell replication time (IE epithelial cells in the oral mucosa replicate extremely rapidly, which causes cuts in your mouth to heal rapidly compared to epithelial cells that make up skin).  Regardless of number of wounds, provided damaged tissues are provided the necessary energy and substrates, 10 wounds will heal as fast as 1 wound.  Caveat: if there are so many wounds that dealing with the byproducts are taxing other body systems, that can dramatically slow healing times and results in many wounds having a significantly longer healing time than one wound.  So there is a threshold where "10 wounds will heal as fast as 1 wound" is no longer true, based on severity and number of wounds.  

Theoretically, wound location could impact healing time as well.  Wounds that are more proximal as opposed to distal could, theoretically, receive more substrate by being 'first in line' as blood flows.  More substrate would support more rapid cellular regeneration.  This almost certainly wouldn't impact superficial wounds, but if the wound is deep enough to impair blood flow to regions 'further down the pipe', it could have an impact on the healing of the distal wound.  

So, bottom line answer: Generally speaking, wounds of similar severity to similar tissue will heal at similar rates, regardless of if there is one wound or ten.  However, if a wound is severe enough to impair or impede blood flow to a second wound, that second wound would likely heal at a comparatively slower rate until comparable blood flow is restored.  As a second caveat, if the combination of severity and number of wounds is enough to put a strain on other body systems, that can dramatically slow healing times.