It's different with Martial though, other than some rare occasions like the first two games of the season where everyone was basically in pre-season mode, when he is not scoring the rest of the intangibles he brings to our attack are almost always there. The myth that he alternates between very good and very poor is just that.
It's understandable with Rashford, he's younger and has had a bigger gap to improve on his technique and decision making, hence when he's not banging in the goals the rest of his game can sway more.
However they're both rarely out of goalscoring form at the same time, which bodes well for our attack so no need to worry about it, and we now also have Bruno who can chip in with goals or penalties if needed
and Mason as well in the wings to add to the output.