I from time to time check the ash. Most now days I will let it burn until it falls on it's own and then tap it off into my Cigar ashtray or in the back 40 depending on where i am smoking it these days. And as the others have said for me it has to do with how well the cigar was constructed.
I will admit I have had some machine made cigars with crap floor crumbs last a good length before just busting off. FOR me if when it hits the ground from falling off the cigar and stays put or mostly stays together then it was a really well made cigar and Very nice and tight. machine made they just fall off to dust lol.
James
Love the Partagas Black. Just don't like they leave the dark color on my lips from time to time. Can't get enough of them