Wow! lots of weird answers. Almost all bows take set over time and often it is the bottom limb that starts the process, 1/4" is the same as "0" in my book. Back when I made equal length limbs a weak lower limb was common after a good bit of shooting I have piked a few when the weakness negatively affected the tiller.
The only bows I have made that didn't take set over time were reflexed bamboo backed bows or bows I made from osage that was that special dense, microscopic early ring stuff we run across every now.
I have really slowed down on my bow making but found my latest heat toasted limbs seldom take any set.