This is just my thoughts. I typically cut thick woods which are 3/4" and even thicker. I do mainly Intarsia and accuracy is the primary concern so that fit is tight. I aim at cutting half of the line. Also, some of the woods are difficult to cut. I change blades quite often as a dull blade results in inaccurate cuts. I really do not care about the price of blades. I may only cut one piece with a blade and make no attempt to reuse a blade. I use either FD Polar #3-#5 blades. I also use PS Woods SuperSharps. My saw is a Hegner
I can tell when I am pushing too hard just by the feel. I have had blades go dull in just two inches.
The point of all this is that the type of project makes a huge difference. I might have a difficult time knowing when a blade is dull on a fret work project or other thin wood with different blades.
What blade to use and how long it lasts depends on your saw, blade type, material type and thickness, your style and a bunch of other things. One needs to experiment and carefully watch how your blades are reacting. There is no secret formula or rule.....just lots of experience.