Yes and no
First, let me say chronographs are an extremely useful tool that I didn't ever think I would need, and then I bought one (a Shooting Chrony F1 from MidwayUSA) and was amazed how far off I was at estimating the speed of the bullets I was reloading (using the manual's estimated bullet speeds).
When you are off by several hundred feet per second, that can mean several tenths of an inch in vertical variance when sighting in the scope at 100 yards, double that variance at 200, triple that variance at 300 and quadruple the variance at 400. Of course, at 500 yards, you are five times off! Three tenths of an inch off at 100 yards would make it 15 tenths (or 1 1/2" off-vertically) at 500 yards! Now figure that your scope is probably set wrong (mine was) at 100 yards and having the trajectory written out to 500 yards was all wrong, the further the distance, the more "WRONG" the written-out trajectory was (I have it written in ink on the left side of my brown rubber buttplate)!
That is why, in the past, I couldn't hit the woodchucks past about 250 yards. I was shooting way too high, thinking the bullet was going slower than it was and the trajectory not as flat as it really is!
Without the chronograph, I thought my bullets were traveling around 3,700 FPS. With the chronograph, the bullets are averaging 4,000 FPS! Realizing just how flat my 22-250 is shooting with 50g Speer bullets, I was able to hit a woodchuck this summer at 500 yards!
As for the question about working up loads after changing lots of powder, no I never did, nor did I ever notice a difference in pressure signs when looking at the primers (the hottest load I have in any of my guns is that 22-250 load which the gun loves at that maximum load). Most of my loads are middle-of-the-road as that is typically where I find the accuracy.
Since I only shoot when I'm serious about hitting something and I don't plink at all with that gun, I'm not afraid of wearing out the barrel in my lifetime.