Welcome to the madness! I've had my trees run all night in the circumstances you describe but I don't think for more than a couple of nights. Means for an early morning check to ensure you aren't coming home to overflowing pails. Dr Tim Perkins, a moderator here, can best describe the freeze/thaw thing for you. But the short answer to your question about how long a sap run can last is....as long as it lasts *shrugs*
Been tapping since 2008.
2018 - 17 taps/7 trees...819l sap, approx 28l syrup
2019 - 18 taps/8 trees...585l sap, 28l syrup...21:1 ratio
2020 - 18 taps/8 trees...890.04l sap...gave away about 170l, 30l snafu'd....23l total for me from approx 690l
2021 - 18 taps/8 trees...395l sap, 12 l syrup
2022 - 18 taps/8 trees....7 sugars 1 red due to #2 having surgery so had the season off....582l sap, 18.5l syrup
2023 - 18 taps/8 trees...all sugars again. 807l sap, so far approx 14l syrup