Don't rush on the speed dial
1) Average stylus life is around 1000 hours depending on the stylus AND depending on the care of the stylus and the cleanliness of the vinyl played
2) You will NOT just wear out high frequencies on the inner grooves (the myths here are like greek saga's) but if not properly cared for you will wear out all grooves, all frequencies. This also applies to improper setup including
Too light VTF
Too heavy VTF
This is how a stylus rides grooves. any dust in those grooves produces heat, friction and thus wear. Diamond stylus's don't WEAR DOWN, the break apart slowly due to microscopic stress factors in the diamond. Heat, friction all serve to cause this. That's why clean stylus, clean vinyl is important
These little bumps are dust
Stylus magnified - NEVER clean your stylus with alcohol - it can actually loosen the epoxy type bond that connects the diamond to the cantilever
Good advices - save for one.
That is erasing HF content with a worn stylus. The effect of wear is GRADUAL - we get used to the sound of a particular stylus - and by the time it is glaringly audible, it is all over for the records played with such a stylus. Believe me, guy with a basic but decent MM cart who is caring for cleanliness of the record and stylus and replace the
diamond stylus every 500 hours or so is much better off than say a guy with Koetsu "streeeeetching" maximum out of his investment BEFORE sending it for a retip - which in this case, if sent to Koetsu, will burn a large hole in the pocket. And no, retips from other sources ( Soundsmith, Benz, Expert Stylus - to name but a few) are NOT going to sound exactly the same as Koetsu originally did. If you like your Koetsu just the way it was when new, sending it for retipping someplace else would be false economy - but I admit it hurts the wallet.
The only fly in the ointment TODAY is the lack of decent test record to document the record wear. I was mighty glad I could get a new/unplayed/mint? copy of the CBS STR 112 test record two months ago - but will only use it for the top 5% of my already tested and checked carts/styli - and most certainly not to show such next to priceless record before and after shaving off HF content by a worn stylus.
I have to get my scanner up and running, for the grim truth about the stylus wear. Quarter of a century ago, when I have been working in a microelectronics plant, Mr. Ernst Benz sent me a few worn out styli to photograph using Scanning Electron Microscope ( some samples of SEM pics shown in your post ) - and since then, I was wondering how to optically confirm the stylus is worn out without access to the SEM ( approx from 500K$ up ) . It can be confirmed by listening, it can be uleashed to wreck havoc with test record(s) - but I finally found the way to show the wear using the very same USB microscope I used for my styli photographs.
So, stay tuned ...