I'm interested in your experience and would like to know how it varies with speaker design. Does precise speaker placement correct for design flaws like poor phase coherence or beamy tweeters in an otherwise excellent speaker? Are speakers with excellent phase coherence and wave guides more forgiving of extremely precise placement? What do you think of YG's claim that their Reference 3 updates make speaker set up easier?
Of course I agree that optimal speaker placement is extremely important. Just trying to reconcile the different views in this thread, where some people find sub-mm adjustments have a huge impact, while others do not.
As Elliot pointed out setup will not fix a poor speaker design. But it will still make the most of whatever speaker that is.
Since you mentioned YG and I mentionet it earlier in my rant we can use that as an illustrative speaker. A lot of speakers in the past few years have moved to horn loaded or waveguided tweeters. This can be a very good thing as it will generally lower the crossover point. A few examples of speakers I have worked with recently with a waveguide tweeter: KEF LS50, Zu, Fyne, Rockport, YG carmel2, YG Hailey, Hyperion. In my experience, with a waveguided tweeter the user has basically two options.
First, toe the speaker out until the listener is pretty much outside the tweeter window. The lisetener is very far off axis and the frequency response is dropping dramatically in the treble. In this case the treble the listener experiences is largely coming from what is being sprayed around the room. This is what the reviewer mentioned in the review that the soundstage got huge and images were large (poorly defined). For me personally, this is not the sound we paid $20K for a pair of speakers to obtain. Some may love this but I don't think $20K is needed to obtain it.
The second option is to drastically toe the speaker in to find THE perfect spot. As we start toeing the speaker in it will actually start to sound worse. I think this is why so many give up on toe-in. They just never make to the right spot. We know when we have reached the right spot because the sound becomes so much quieter and clearer. The tweeter noise and the room noise drop dramatically. This is the actual sound that we paid $20K to get.
A couple more thoughts on this. It is no wonder that YG recomments toeing the speakers out. It is much easier to get acceptable sound (Not great sound). And it can be achieved much faster. When the distributor/sales guy/dealer is setting up a pair of speaker in the store or at a show they also typically want a large soundfield that sounds good to a large audience and not great sound for a single seat. So again the toe-out thing works in that scenario. Getting close to the correct toe-in but not nailing it is not forgiving at all. The YG tweeter is very detailed and can easily sound bright and edgy if not perfect.
In the end it is up the the user to decide what kind of sound they want.