i prefer to have my 50mm 1.8 on at all times because of the versatility and size. Would you happen to know the "prime" focal length to shoot at on the 24-105, i assume some would call it a "sweet spot" for sharpness and cleanliness? lol
The sweet spot ... I believe it is the aperture setting at a particular focal length of a zoom lens or the fixed focal length of a prime lens.
Take a look at the following link
Canon EF 50mm f/1.8 II (Full Format) - Review / Test Report - Analysis
That is the 50mm lens on a FF body. Scroll down to the MTF chart. The center optical performance peak at F/4. But overall performance (center and broader) is best at F/5.6. So I will say the sweet spot is F/5.6 for the 50mm F/1.8 lens.
As for your 24-105mm L lens, you can take a look at here
Canon EF 24-105mm f/4 USM L IS (full format) - Review / Lab Test Report - Analysis
In general, center performance peak at F/5.6, but overall best performance is around F/5.6 - F/8 on various focal length. And that means when you want sharpest photos, set the aperture to F/5.6 to F/8. But of course, it really depends on the situations.
As for the focal length, you just need to set the focal length based on what you want to shoot. Not because the lens perform better at a particular length. Like you want to capture a image of a distance object. I am sure you may not want to set the focal length at 24mm.