When I started I heavily relied on the discrim knob and learned where targets broke to get an idea what I was digging. I am re-learning as I use the Cibola, don't know if the audio on Cibola is similar to the Vaquero but maybe someone here that has both can say.
Last couple of years I had a lot of trouble with the Tejon due to a failing ground balance pot that caused all sorts of havoc. Thankfully couple good people helped out, Carl that confirmed the issue and Flydog that pointed out a supplier. After replacing the pot I can hear incredible variations on targets.

With a base setting of breaking on iron nail which on the Tejon is just at the iron line the following happens:
Majority of small iron is eliminated, larger iron will give a crackle on edge coil detection. Large iron will tend to have a reverse roll or bit of a thuuk to it (loud/soft/loud). Fall off is long like a can.

Thinner gold rings or fine gold rings, earrings, pendants, silver coins have a roll tone and tend to sound nice.

Copper nickel alloys ie Nickels, Flying Eagle cents are bit sharper and have a bark in all metal mode, slight tone roll but very easily to confuse with can slaw.

Aluminum, aluminum screw caps are typically loud and flat. Often have a pop or click at start and end of tone. All metal mode you will hear how flat.

Now the hardest part... determining depth based off volume of target. This took me a long time to be able to get a good sense of depth and size of a target that ultimately effects the audio response. Very easy to get tripped up on squashed aluminum screw caps and think they maybe a clad quarter or even a large cent etc. Other targets that can trip me up are balls of aluminum foil as they can sound like a thin ring. One way I test depth and size if not sure by my pinpoint (all metal) pass is lift the coil to hear how fast the target falls off. Cans will hold a tone much further than any coin. I believe you do that already if memory serves me correct.

Now the Tejon threshold has no effect on audio to depth of target which some call super tuning so it has a constant.
From what I am discovering on the Cibola is to run that threshold to a minimum so the audio isn't clipped on majority of targets. I will kick it up on a fringe target but put it back after.

Descent set of headphones really help. When testing sounds on targets keep the coil about 6" above to get an average sense. If the coil is too close they will all sound too similar and flat. Again Depth plays a big roll on audio response.