Yeah, I've never used spectro's so I can't say one way or the other.
But I work with old timers who definitely do things the old fashioned way.
If you are in the print business, you should have a good enough eye and an excellent working knowledge of color theory. There's really no reason why you can't print one sample test, see where it is, determine what colors need to move in what direction, and simply make it happen.
I do all my color matching (and yes, it IS color matching. There's no color simulation in fine art giclee printing. These people want an exact match, and we deliver) in Photoshop. Basically the only adjustments I need are levels/curves, hue/saturation, and selective color.
If I can't get it done with those options, then I've failed, not the equipment or my technique.
Yes, printing lots of proof is wasting time, energy, and money. But we charge our clients a fairly hefty proofing fee, because they want an EXACT match to their art. And the more you proof, the better you get. There are many times we will take a scan of a painting, print a raw proof, look it over and nail it on the first or second try.
There's no substitute for color theory knowledge.
I agree that your business (art reproduction) is a very different animal than
sign and display graphics. I would guess that you are using very different machines with a higher number of ink channels (Epson / Canon / HP). These machines often times have 8, 10, or 12 unique inks. You are also likely printing onto a fairly small population of coated photobase papers and coated art canvas, and the output is expected to be used exclusively indoors. The business segment that those machines are intended for is reproduction of fine art, and that market places a very high priority on gamut, color fidelity and accuracy. Running costs for traditional aqueous printers are relatively high (more expensive ink and media), which is not a major problem in this market segment, due to the relatively high prices that are charged for this output.
Those same traditional water-based Epson, Cannon, and HP printers are also ill suited to the market that this site caters to - the
sign and display business. In this market, the ability to output to low-cost, outdoor durable, uncoated media is essential. This market has not historically placed it's highest priority on gamut, but rather on low running costs (ink and media) and outdoor durability.
The process you are describing is a classic 'closed loop' approach to color. You are modifying the colors in the file (using a tool like Photoshop or Lightroom) to make the printer produce the desired result on the media in question. That approach can work well when you are an experienced operator (which I'm guessing that you are), and the number of print-centric variables are low (few classes of print media), and often times dedicating a specific machine to one media.
As you say, there is no substitute for experience and practice when using a closed loop approach to managing color.
When you need to print your jobs jobs on very different printers (say latex and solvent and UV), or very diverse types of media (SAV, textiles,
paper, backlit film etc), closed loop systems fall apart very quickly. For those willing to investigate a different approach, here is a link for an outstanding training program that is produced by IDEAlliance (I have no affiliation with it):
http://www.idealliance.org/videos/CMP2.0-Lesson1_Introduction_Color_Management/index.html
Happy printing (using any approach that suits you)!