The weak springs appeared to be early-on in the 4 leaf period. My 2012 had them, and they were awful, although that wasn't so apparent until I changed them. We toured Scotland with the old springs and that's what persuaded me to get on and do it.
Otherwise leaf springs go on and on unless they break. My first leaf spring job was on an MG Midget. I broke the main leaf on day 1 of ownership, and went through a few in the following years.
Could it be a MAM problem
