It depends on how many of your runs are on extraterritorial property, and what kind of other healing you have available. For instance, relatively few of any of the Missions series or even the non-Missions runs published since the start of 4e take place wholly or even mostly on extraterritorial property. Remember, just because someplace is corporate property, unless they're an AA or higher, they aren't extraterritorial.
That does drek all for you if you're on a run inside an MCT Zero Zone, but if you're at an A Corp, even if it is an MCT subsidiary protected by MCT's security company, that isn't MCT property, and isn't extraterritorial. Runs in the Orc Underground, or the Barrens? Not extraterritorial. Runs on political figures? Not extraterritorial. Runs against gangs, syndicates, or policlubs? Not extraterritorial.
So there's lots of places you can use it, even in a runner's lifestyle. The more Pink Mohawk your group is, the more likely you're going to need them, honestly. The Black Trenchcoat crowd tends to view combat as the last resort, and then it is more to disengage than to take down the enemy, so they tend to acquire fewer bullet holes that need patching, and the ones they do get can be dealt with easily enough with magic or a first aid kit, at least until they get to their street doc. Even when my character has DocWagon coverage, I've never been in a situation where I needed it. If I got tagged hard enough that the call went out, I was dead by the time they got there.
So, how much you need DocWagon is a direct reflection of how much fighting you do off extraterritorial property.