This is after 3+ years of daily collections calls from half a dozen companies pursuing a high five-figure debt.

The takeaway being: debt is a business phenomenon and discussions about it are a negotiation. I negotiated hard; when my offers of partial repayment were refused I never answered their calls again. In fact I created a special, looong outgoing voicemail message that sounded like I was answering the phone ("Hello? What? Hello? Are you there? Okay, a large pizza? We don't do gluten free!") and forwarded any unrecognized number to it straightaway. Just maybe that made someone laugh and they decided to toss my file.

Had I gotten a summons, I was advised by a lawyer to demand a witness. I never tested that tactic, but I do suspect that if someone had the means to extract money from me they would have, and they did not.

It's all about recoverability and risk over return. Most of the time a 5-figure debt will be worth the effort. When you start getting into $5k or less debts, it's sort of a crapshoot. The original owner of the debt will often sell it for pennies on the dollar, at which point a collector will do their best to get as much as they can out of people without a civil case, because civil cases are expensive and there's no real guarantee of return (people with no money, people on the verge of bankruptcy, etc).

The general advice is not to negotiate at all with creditors. Once something's gone into collections, you will see no benefit to resolving the debt other than mitigating your risk of a law suit. And even at that point, the first phase is a mediation option wherein you'd again be able to throw out a number, do a payment plan, etc.