yes ,I do.. I hunt a very old site that has over 200 years of ground up whatnot,nails,cast iron bits of stoves,car parts horse shoes, coal ash,pig iron,aluminum foil bits,etc..Ive found 5khz works best at hitting copper and brass while giving me a fighting chance against the above listed debris..I’ve tried every combination I can come up with but 5khz is most productive at this site... multi frequency at this site gives way too many good signals on iron which wastes a lot of time and effort.. 10 and15 kHz are just a little too frisky on the small aluminum bits... really all depends on how the site reacts to your settings... I haven’t found any use for the 4khz ..you would think 4 and 5khz would probably be similar but they certainly are not in my opinion...
I just reread your post..park1 or field 2 seems to work best in the above mentioned site..mostly park 1 avoids the iron and small bits of aluminum while still hitting on small flat buttons and coins which can also be a somewhat low tone item..