I'm not sure if I should post this here or in the woodworking group...

I'm building a workbench out of 2x4 Hem-Fir studs and I want to know
the maximum span I can consider for the rails. I made one 15 years ago
at my mother's house and it still is a very sturdy bench. That one has
57" rails lag-screwed to notched legs. But I have a bit more room in
my garage and I wanted to build an 8 foot bench.

Should I add legs in the middle of the span? Otherwise, I'd have a
nice wide bottom shelf and a wide open space underneath without a leg
getting in the way.

Mike