138S: "If wanting to know well what you are to get then there is a single way: spot metering"
In fact, I also use the one with an external spot. The discussion instead concerns multi-spots.
I do the multi-spot myself with pen and paper starting from various single spot readings: I draw a horizontal graduated line on a sheet and place all the readings in EV, then I decide which area I want to reproduce in the medium tone (to have there the maximum detail) and I put this reading at 0, the others I get for difference with precision of 1/10 of EV; then I simulate the possible results with various exposures based on the film I use ... and in the meantime the light conditions have changed so I am forced to do it all over again!
Expose for the shadows and develop for the lights !!!
No way based of averaged spots will give you total control on what you do.
In LF, as we can make a custom development for each individual BW sheet, we ensure the right exposure for the detail we want in the shadows and later we meter highlights to know if we have to underdevelop to not get too high densities there, this is the way we nail exposure for each sheet, just spot metering two spots, one to determine exposure and the other to determine development.
With rolls we cannot make an individual development for each frame, so procedure for negative film is slightly different:
1) Determine exposure for shadows, say we place our shadows at -1.
2) Check mids and highlights to know how much they are overexposed... and to find if we should sacrifice more quality in the shadows to not have too high densities.
With slides in rolls, also we cannot make an individual development for each frame, so procedure for slide film is slightly different, for example:
1) Determine exposure for highlights, usually we don't want toasted highlights in the slides, say we place our highlights at -1.5.
2) Check mids and sahdows to know if we need a graded ND or if we may want to consider to have a loss in the highlights to have mids in the right place.
This is the kind of custom "multi-spot" that's works, you don't average spots, you check one or two spots and you quickly balance your exposure in an smart way. This is faster than trying to guess what the multi-spot calculation is doing and adjusting with the compensation dial.
Many times, for portraits, you take just one spot reading in the right place, that's all. If you take an additional second reading this is not to meter but to adjust illumination, key vs fill, to get what you want.
My preference, multi-spot... yes !!!
...but I decide what spots and how I balance, to me it's the faster way that allows total control, but YMMV.
I'm a relative newcomer to LF, but metering for LF refined the way I presently meter.
A good exercise is using Sunny 16 for a while, it builds intuition and self-confidence in the photographer.
Ansel Adams metered the "Moonrise, Hernandez, New Mexico" by smelling the moon
https://en.wikipedia.org/wiki/Moonrise,_Hernandez,_New_Mexico
See how many decades later still he was remembering all metering details...