10 days
EE here and the math was hard. Barely touch any of it now, but I miss it and I wish it was more practical. Maybe it was in training me to be very precise and methodical.
But in solid state physics, having the math to follow and understand maxwells equations, e=mc^2, and Heisenberg’s uncertainty principle. Priceless.
My own enjoyment. But EE degree has certainly paid for itself.