Landing strikes is not simply about being quicker than the opponent, more so it is about throwing off their defensive “rhythm.”
“Attack by combination” is probably the simplest way to teach this to someone because all it really requires is for you to throw a sequence of techniques. For instance, I throw a jab and you cover, so I throw a straight right to your body (which either lands and causes you to fold forward, or brings your elbows down and together to block), and then I throw a left hook around your guard and catch you (or throw a left “head smack” to your temple knocking you off balance and placing your weight on your left leg and follow up with a right round kick to your lead leg, or right inside trip/Ouchi Gari into a takedown, etc…). The idea is that in order to defend one target/line of attack you must open/leave unprotected another one. My attacks are therefore meant to entrap you into eventually giving me the target that I want. Should more than one attack land, great, but on a well designed combination it shouldn’t really matter.
Again though, that’s just one method.
Another simple (but not necessarily easy) one would be a change of speed. Throw two or three jabs as fast as you can (“probe stepping” if you want to minimize risk of getting countered hard), then step in fully and throw another jab slow, heck, even telegraph it by leading with your shoulder. Your opponent’s defensive timing will be set to expect the impact of that punch to occur in the same timing that it did during the first couple/few, and thus will execute their defensive action to thwart that. However, because you slowed down/changed the timing of sequence of moves, their defensive action will be too early and you therefore largely or wholy ineffective. You can’t of course be moving in “slow motion” but must simply take off just enough speed that you come in “the back door.” This is the same phenomenon of a baseball pitcher throwing a few fast balls and then throwing a change up; the batter will react too early and thus be way out ahead of the pitch and whiff.
This is definitely harder to teach and do than combinations though, which is again why it’s generally not taught first to beginners.
And again, these are only a couple ways.