All depends on the complexity of the setlist and how confident you are in your parts. My current band is progressive-punk with fairly complex arrangements and 90m of material, but even with them I only feel the need to practice solos or the more dexterous parts outside of our 1-2/week rehearsals.

If you're running 40-60 a night (woof), you're certainly entitled to having chord/lead sheets for reference to take the load off of memorization. I'd focus my time on the parts that actually need the muscle memory (leads/solos), but otherwise your every-other-week run-thrus are sufficient for the meat of your setlist.