Not really, wifi is very low power, and very temperamental to local geometry and environment.  Someone walking by is enough to make it change.  Microwave ovens or wireless phone handsets will profoundly disrupt the signal.

Most operating systems do a bunch of averaging over time to smooth out the fluctuations to give the illusion of stability.  It's also a dirty little secret that many implementations fiddle with the value to make their products look "better".

"Link quality" doesn't really correspond to anything physical - it's a computed function based on the signal strength, noise levels, packet bit errors, and other factors.

Also to add to all the noise are all the other WiFi networks that are out there. I was having issues with my Chumby staying on the network as it in an upstairs bedroom on the completely opposite corner of the house to my WiFi router, which is in the basement. I really did not want to move either device, so instead I did a quick site survey using my laptop to see what other networks were in the area. There were several other networks I could see from that same bedroom, so I took note of what channels they were using and moved my router setting to an unused channel. As the majority of people simply use the default settings the majority of networks, including my own, were all set either to channel 1 or channel 6. This solved my connectivity issues with the Chumby and improved the performance of all my wireless devices.

Unfortunately the WiFi band is unlicensed, so there are many devices that use these frequencies. I recently added a pair of wireless speakers which just about killed my wireless network. The speakers defaulted to the exact same channel as I was using for my network. The speakers seemed to always win the interference battle. I was able to change the frequency of the speakers to channel 11, but it just shows that with all of the wireless devices out there you really need to keep a frequency plan in mind. I know it may sound like a bit too much, but it really helps out. I initially setup my router to channel 1 to be far away from the microwave oven, which can interfere with channels 7-10.  Since most of my neighbors were using channel 6 and only a few using channel 1, I chose channel 3. It is still not perfect as channel 3 overlaps both, but it has really helped me out.