Really? What if you take a few year break from contracting? (a mini-startup, personal projects, perhaps you just get a regular job for few years to sort out your finances or build a house). Are you supposed to keep networking with your previous clients during this time when you know well enough you'll not want to take any jobs they may want to give you?
Then there are all those people that transition between technology stacks. I did that few times so far (Linux to Windows, then Windows to Linux, vmware to aws). Your past clients will most likely want you for the stuff you worked on in the past. Also some people relocate internationally, perhaps to different time zones. Among people I came to know over the years many did that.
So I find this idea of "constant networking" work in a very narrow set of circumstances.
