Really… then why can olympic lifter progress by basically doing the same thing over and over for years?
I think we create “laws” too easily. While I’m all for variations in loading schemes and methods (e.g. pauses, slower tempo, etc.) I do not believe that there is a need to change the big exercises often. If you train above 90% all the time, maybe. But then it is worth questioning if always training above 90% is that smart for normal individuals.
As for smaller movements, it’s more a matter of them not making a huge difference in muscle recruitment. If you do a preacher curl on a standing barbell curl, honestly it’s still a curl. The neurological component isn’t that great. I do not see a NEED to change smaller exercises more often but there is no harm in changing them often. Basically it comes down to staying motivated and some people like to vary things others like to stick to the same thing.