With the 2hr Endurance workouts in Polarized Plans, would it be possible to split a workout into separate 1hr sessions to fit in during the day? Or would that negate the effect of the workout?
It wouldn’t be a total loss, but two hours steady is probably a bit better than two one hour sessions. If you can only do the latter it’s better than nothing.
One of the more recent podcasts did a deep-ish dive on two-a-day workouts, probably worth a listen for you.