When I lived up north with loads of oaks and maples I used a backpack blower with a section or two of downspout connected. Worked pretty darn good getting the leaves out. That was after
I had tried the foam inserts, garbage collectors. Also had the builders grade plastic guards, more garbage.
Moved south.
Pine needles? Yeah, by the truckload

having a backyard neighbor with a half dozen pine trees on his property. They are impossible to get out, those needles stick to everything especially the hangers, and jam up the downspouts.
And if you have round holes in the gutter guards, the needles will find them, and you won’t get them out without putting up a ladder.
After doing my homework, I had a contractor put a fine stainless steel mesh filter on. Looks like the one below but with some squiggly lines, not the straight lines pictured, that keep everything elevated off the surface. If wet leaves collect there, I haven’t seen any, they will get blown off once they dry by the wind.
Same with the pine needles, they will not get stuck. The mesh is too small for them to plant their flags.
Best thing I could have done as I have not put up a ladder since they were installed about two years ago. Water flows free, no jams in downspouts.
They may have to be cleaned sometime, but it won’t be 5-10 times a year like before, and I’ll just pay someone to do it if/when it clogs.