When 4G first started I noticed really fast 4G service at 2am in the morning, but super slow during the day.
Most of the cells I was connecting to were in the city.
Over time as they built out the 4G infrastructure it got better, but for well over a year if you were at work and struggling to get mobile bandwidth then a switch to 3G was almost always significantly faster, double upside because everyone wanted to be on 4G and deserted the 3G bands, so no bottlenecks.