Is this smart?

Hi everybody
I was wondering if anybody would be able to help me with a question and a problem i have.
Ok,first the question:
Seeing as when bench pressing, having a wide/close grip, or doing an incline/decline press works out different areas of the pectorials(so i’ve heard), i was just wondering if instead of doing 3 sets of standard flat-bench presses, i do one set of those, as well as one set of wide-grip inclines and one set of close-grip declines. Would this be a more efficient or more unefficient way to work out?
Now to that problem: on my bench, as with many benches, i have a well-padded leg extension feature. I put about 10kgs of weight on(which i know i could easily handle), but to my surprise, when I attempted to do an extension, my shins started to hurt. Now i don’t know why this is happening…I always thought i had fairly strong bones…could anybody shed some light on the situation?
Thanks guys

try putting some padding on the bar. or, just get rid of the thing and squat and deadlift.

Yeah, melt down that leg extension machine into plates or anything else that can be used to build muscle.