I’ve just begun playing and it took some time for me to really mould my shoulder rest. I’m more or less comfortable with it on. I have a short neck though so it seems like the rest can be at times too high (even at the lowest height), depending on the clothing I’m wearing (bulky sweater). Thinking my issue may be related to the chin rest too, but my instructor doesn’t seem to think I’m having much issue with the set-up. I may change up the chin rest once I get more time in.
So, yeah.. personal preference for most people. I went through three different shoulder rests before I settled on the one I have (Wolf Secondo). May still change later on.