WOW!! That sure looks ugly, she did a good job.
Like above, what are you using under the bandage/dressing? Leg wounds are nasty and seem to heal a lot slower than anywhere else. I would recommend using manuka honey in any wound, it works wonders. My broodie fell on a star-dropper (metal fencing stake) over christmas time and it went through her shoulder (not bone though) I could fit my whole fist into the cavity. Eventhough I couldn't bandage it I made a poultice of honey and used a gauze padding that stuck to the honey. The would was healed in 2 months! Manuka Honey is not found in supermarkets, really only health food stores.
As for keeping it bandaged, yes! This will keep all the nasty foreign bodies out of the wound. When you take the bandage off, clean the wound with a good wound cleanser, then spray with a Sea Minerals spray (really good for tissue growth) Later on if you see proud flesh forming use Yellow Lotion (if you can get it) this will dissolve the proud flesh and you wont be left with any ugly lumpy scar tissue.
And I totally agree with you situation with the vets and emergency calls. A horse of mine cut the digital vein in her fetlock one day while I was at work. When I found her she was standing in a great big pool of blood and when I rang a vet, not my regular, he said he was at a swimming lesson and couldn't get there!!! My horse was bleeding to death, while he was in his speedos getting wet
Luckily I got hold of my usual vet and he came out straight away, stitched her up and left me a god awful bill, but it was worth it.