said by silbaco:
If you can't get those speeds in a real world test, then they are nothing but a waste of your time.
All speed tests are short duration tests, but even though results can skew higher, those can give an indication indirectly of your server's load...if speed test site has the bandwidth.
All speed tests are biased in some manner, but as noted, using a good site for a file DL can be a better test.
Main point is if your web surfing works for sites with adequate bandwidth, and file DLs/Uls don't take forever, speed tests are not needed.