To be perfectly honest many receivers have a scan function, but I find
it to be of little value on shortwave mostly because the threshold for
stopping scan is way too high on all the receivers I've tried. It
misses lots of weaker signals. Spinning the dial is in my experience a
much better way to move through the dial. With one finger you can move
through the band at any speed, stop, reverse, etc. Much more
cumbersome and imprecise with a scan button.