The first thing you learn (or should learn) in politics is that people don't care. Or if they care they don't pay much attention. If you want a demonstration of that fact you can either wade through the libraries of political science literature examining this phenomenon or spend a day asking random people about politics.
If you are reading this (then thank you firstly) or any other political blog you are far far far more interested in following politics than the average person. But because people who follow politics tend to group together, whether on blogs, journos, party members, the Westminster bubble or whatever we forget this sometimes. To our cost frankly.
Most people never hear about the day to day things we obsess over, drops in a lake, at best people feel slight ripples and it with other similar stories builds up to a slight change, but that is really all. To switch up the metaphors you're trying to understand shifting sand dunes by examining each gust of breeze. On their own they only move a small number of grains of sand. Sometimes you'll get a major story/gale that'll cross over into the wider public consciousness and make a big move, but they're rare.
If you want so see any effect don't score leaders on PMQs, score leaders on the segments of PMQs that get shown on the 10 o'clock news. Or how the other media says that they are doing (often at best tangentially related to how you believe they're performing). Then apply this same methodology to all political stories. If you want to predict how people will act and react in the future to politics, you must first be realistic about what they perceive and what they're reacting to.