The rate of change is of course an important factor, but some things like the order of how you installed fonts (which depends on the order you installed the software that fonts came with) or the plugins you have installed in your browser are still going to be constant.
What we saw was that people tried to spoof their UA only made it more unique. (E.g. your UA says Internet Explorer but you have Chrome specific plugins). Or even worse if you have a completely unique User Agent.