1970 Dodge Dart Camshaft

It's actually pretty important on an 8/1 engine. On a 318, the difference of 4 degrees might only mean 4 to 5psi cylinder pressure. But the difference in low-rpm performance can be over 5.5%.
Again 5.5% doesn't sound like a lot, but it is the equivalent of one rear gear size, say from 2.76s to 2.94s. And if you've ever done the swap, you would know how significant that is.
Another way to look at it is, as an increase in stall-torque, of 5.5% plus. Again this does not sound like much at stall speed, maybe 4 horsepower, but at peak power it could be as much as double. Where you gonna get 8 horsepower for the time it costs to make the cam-timing right? That's almost half of what a 4bbl carb might make.

To put this into perspective, say you didn't degree the cam and did install a 4bbl carb. for a potential of plus 20hp. But the cam went in 4* retarded so you only realized plus 14 hp. You couldda had plus 8hp with a properly timed cam. So how much did the 4bbl system set you back for the additional 6 hp? Now yur getting it.
Now, this is not exactly how it works, but the point is the same, take the time and put the cam where it needs to be.