Yep, this is what my parents used on their cottage with 6 mature pine trees surrounding it. You need the mesh to keep the small needles out of the gutters, although the ones we installed has the mesh on top. Maybe these are installed upside down?
Then just blast them with the leaf blower once in a while to clear the accumulation.
If you want to try these, I'd go with the ones with the screening in them like Warstud's.
I made the mistake of using the "Frost King" version that are basically just like these without the screen. Smaller whirlybirds and whatnot fall right through and plug the downspouts anyway.
I recently had to get out my 24' extension ladder in the pouring rain to pull the end 'gutter guards' so I could unplug the downspout ends. Good times and a waste of resources for me.
But now how often?
Id imagine that some junk can still get caught up in these things, and when it does, then its next to impossible to get into the gutters to clean, no?
I installed some of the ones with screens where the silver maples drop whirlybirds, they work well for that, but even still, they get caught in other places and Id imagine that when they decompose, they leave some organic behind that can ultimately clog gutters anyway.
Just thinking out loud though...
Do these help with ice and snow in any way?
OK, it would seem the easiest and best gutter guards for pine needs especially (and leaves also) are Leafsout. They have a fine SS mesh rather than holes drilled in aluminum. I think the mesh is 1200 holes per square inch. Too fine to a pine needle to get stuck in. They are on Amazon and for under $4 you can get a 6" (long) sample which I did to see if it fits.