Honestly I have a gross backlog (thank you PS+ sales & freebies), and I'm pretty good at keeping my nose to the grindestone of fun - got free time, quick pick a game, and get to it. But I still find myself wasting time trophy hunting, at least in games that only take a single playthrough to 100%. (Those that require multiple runs are fine, they get put in the "beaten but not finished" pile.)

By playing them.
I already have a huge backlog this gen and it's not getting better since I buy so much new stuff every month, but if I didn't just boot them up, I wouldn't complete any of them. Therefore I usually play 3-5 different games a day. Not for long obviously, about an hour each. That way, even if I don't terribly fall in love with the game, I'm still doing some progress.

Exactly. At least, that's what I keep telling myself while I look at games I've had sitting on my shelf for three years completely unplayed.

I'd a massive ps3 backlog about 3 years ago. By the time I got down to the last 10 I was struggling for motivation to finish it. Hence why I saved RDR till near the end. It motivates me to finish them.

When I'm finished with yakuza 4 I'll play RDR. Then it's Jak 3 and yakuza 5. Then my ps3 backlog finally complete. And I'll move onto my ps4 backlog!

I usually pick the longest ones first. I go for platinums if it's reasonable (gave up on RE7 because I hate not having checkpoints) so that time factors in. I'm all caught up now for the first time in awhile! Was gonna get for honor but it's mostly online it seems and doesn't have the offline splitscreen that was previously promised so Horizon is next.

usually wait for winter and then i just start playing. ive beaten at least 15 games this winter and counting ..

Just pick a game stick to it from start to finish, most of the time. Switching back and forth doesn't help at all for me. With Fallout 4, The Witcher 3 and FFXV, I may never be done -_-

I don't get into a lot of games and some just don't have a high replay value so I generally stick to just a select few I play most of the time. Basically this prevents a backlog from occurring. That being said I do find it hard to 100% some games once I've done most of what they offer.

I dont go for trophies, or collecting every single item/equipment/collectibles, or max lvl. I also quit 8to5 job and run my own business so i have plenty of free time

^This.  I've got tons of RPGs in my backlog.