94-97 Accord - How long do front springs usually last?

I have a 97 accord with 140K miles. I am wondering how long do the
stock springs last before needing to be replaced.
I recently replaced a set of worn Michelin X-ones with a set of
Goodyear Assurance Comfortreds which have received rave reviews for a
smooth and quiet ride. The ride however didn't meet expectations. So
after finding worn and deteriorated rubber damper mounts, I had them
replaced. The ride did improve significantly for a while (perhaps while
the rubber was wearing in). Now when I go over bumps, highway expansion
strips, the impact is quite harsh. I don't want to keep playing the
game of trial and error and just randomly replace suspension
components. I did replace my stock struts with a set of Monroe
Sensatracs about 50K ago. 50K on a set of aftermarket struts seems
within their usefull life, so I have a tough time believing they could
be the cause. Although I did spend the past 2 years in Michigan (with
potholes from hell) Some have suggested that the springs should be
replaced. They do squeek when I go over some speed bumps. This is why I
am asking how long they typically last and is there ways to test
specifically for worn springs.
Thanks

 

squeaks could be bearings

 

coil springs last until they break, which may be for ever if they're not
rusted. there's no mechanism for them to go "soft" in the steel, and
there's no major wear points like in leaf springs.

 

Coils slowly loose some tension over time but it is minimal.
Enough to be barely measurable in 10 years.
Plan on replacing them around the year 2032.
Your shocks are shot. The internal valving is worn out.
Monroe makes shocks for the masses. I won't put them on anything I own.
Odds are the sway bar bushings is where the squeek is from.