Originally Posted by
techsensei
...instead of the rocking you get with a drift punch (which tends to prevent you from removing the cup).
I've never found it a problem; I keep an eye on the cup and move the punch when the cup budges. Once it's moved, you can usually just give it a tap every 120° or so without paying too much attention.
Mind you, that's for 1" steerer headtubes... the larger the diameter, the sketchier it is without a press or proper flared punch... I've found removing large cups a bit harder without the right tools, and installing them can be kinda tricky.