Admittedly there are slow drivers, slow units, poor adhesion... it could be anything.
On my own commute, there are sections of jointed track and certain waypoints that you can tell when a driver is going a bit quick. Ive only ever once thought though "hmm, he best slow down a bit" only for the TPWS to kick in at the PSR and the train come to a complete stand. That, I am fairly certain, was driver error, as the power was on for much longer than normal (wazzing through Carleton Crossing on high power, when usually its coasting through there to the 35mph at P-l-F) and Im reasonable certain is was straight in to a Step 2 brake before the systems took over.
Sometimes if we're lucky, a driver will ignore the latter end of the 45mph near Bamber Bridge, and apply power just as the train passes under the A6 overbridge. Although its difficult to tell much what the speed is most of the way, the jointed track near Pleasington is usually a give-away that we're either travelling faster or slower than normal... the latter almost always when in a Perkins powered 158!
