Bit of a pointless thread lol.
None of us get 50mb 24 hours a day. The speed will vary all the time between 20-50mbps and because we dont do a speedtest every second of the day its impossible to say we get 50mbps 24/7
Take for example 'Thyroid Help' His speedtest showed he was 20mbps+ off, Cant really say he is not getting 50mb's download because 1) 'Up to 50Mb Speeds' 2) If he retook it later on the chances are it would have shown 48-50mbps.
You could do one test and get 51.07mbps and do a second 3 minutes later and get 28mbps... Nevertheless we are on 50mb and unless there is an issue we get the speed advertised.