Think your speakers are positioned correctly?

It took me almost three years to get my speakers dialed in just right. I would listen for a while, make adjustments and listen a while again. I too make 1/8 to 1/4 inch adjustments. Speakers seem to move. I don't know if someone bumps them or what happens, but I remember one time things didn't seem right. I got out the tape measure and one speaker was out of position by nearly an inch.
The most obvious tell for me is the imaging and sound stage. Images seem a bit out of focus if one or both speakers are not dialed in right and the sound stage can seem compressed. Something else also seems off with the sound to me if one speaker is out of position, but I don't know how to describe it. I made the final toe-in adjustments by ear and then measured. Both speakers ended up within 1/4 inch.

I would get my sons to help me, but they would always sigh and roll their eyes a lot. My initial setup goes back a few decades. Whenever we moved and I had to start fresh with a new room I start with about 6-7 feet distance between speakers, depending on room size (width) and distance them from the back wall as much as I can and still have at least 7-8 feet distance from the front of the speakers to where my ears are. More distance from the speakers to listening position is better, but I have always liked the speakers at least 24 inches from the back wall.
From there, if you have the room, try moving the speakers further apart. Try to keep an approx. equilateral triangle between each speaker and your listening position. Move the speakers further away from the back wall if you can. Keep going until the bass sounds too weak. Distance apart will affect this too. If you can, keep moving the speakers apart until the sound stage falls apart or has a hole in the middle or the side walls are too close. Side wall distance is more important than separation of the two speakers if they are already greater than 6 feet apart. Some speakers can work 8 or 9 feet apart. Mine are 108 inches on centers apart and 38 and 1/4 inches from the back wall to the center back of the speaker. The left is 56 inches from the side wall while the right is 76 inches. My listening position puts my ears 120 inches from the tweeters. Of course, I can lean forward 12 inches easily enough but I like the 120 inch point better.
Toe-in is speaker dependent. Some speakers work best when the drivers are facing you (imagine a mirror on the front of the speaker and you can see your face from your listening position) while others sound best facing forward. Just start toeing in in large increments until the sound is better then worse, then
move back in smaller increments until it is dialed in. This fine tuning of toe-in should be done last because speaker position to walls and listening position will affect how toe-in sounds.

As I was saying, this whole process takes a while for me. That's because I would listen for a month or two and decide to try tweaking something. I might move distance apart and then back a little again. I would also move the speakers closer to the back wall, but always end up pulling them back out. Toe-in is something that I fiddled with for a long time before getting it dialed-in. That is because speaker position impacts toe-in.