Virgin Media speeds when you look at the trend over time appear to have a cycle at the national level (https://labs.thinkbroadband.com/local/ and click the orange cable button)

A rise for a couple of quarters then a dip and then a recovery suggesting the speed upgrades and improvements do have an effect, but the cycle is regular.

If you look at a smaller area like e.g. Crawley https://labs.thinkbroadband.com/local/index.php?area... the effect is more pronounced.

I have had Virgin media for several years, and have always been pleased with the speed and service, it is never less than 100 Mbps. I live in Leeds.