Between jobs I had my wife's insurance cover me for a weekend. The HR types I talked to made very sure that I had documentation of unbroken coverage, saying tha

Between jobs I had my wife's insurance cover me for a weekend. The HR types I talked to made very sure that I had documentation of unbroken coverage, saying that it was pretty common for insurance companies to argue pre-existing conditions for even a day of not being under some insurance umbrella. I believe this is no longer allowed under relatively recent law.