Hi Mike & Al,
I'm thinking back to the late 70's & early 80's. We hand measured all our own drivers, we listened to each driver individually for beaming/dispersion characteristics, based upon the basics of each driver, we chose crossover slopes for the drivers character and to maximize phase and time alignment... Yes, even then at least at Marcof, we practiced time and phase alignment. We would then build the piece, listen extensively and make changes based upon our sessions. It was quite a process.
Today, as long as the measurements are correct, I can run a program and know with a high degree of accuracy pretty dog on close what a speaker will sound like.... Its never far off like "wow, that fooled me"....
Yes, after listening there is tweaking, but these days, it usually isn't much. The big deal is to understand what different slopes and combination of slopes sound like. Looking at Frequency and phase charts carefully and then proper choice of slopes and frequency of crossover, you can come fairly close maintaining decent phase slopes using odd order crossovers, its not always 6db per octave slopes required like so many believe that you must have.
Ok, a bit off subject, but I wanted to add to the earlier comments.
Tim