Setting heat too high

Hey guys, I keep my heat at 74 usually during the day but today it seems to be having issues getting over 72. It’s been running non stop basically so I turned it down to 71 to give it a chance to rest?

I know there’s supposed to be a +/- differential of what the units can even do like if it’s 0 degrees outside it can only heat it to X above the outside temp right?

But what are those limits? I’m fine with turning my heat down a bit, but does this indicate that my heat / insulation is in need of an upgrade?