I love my Platemates (which I've had for eons). I use the 1.25 lb ones all the time (2 * 1.25 lbs on 10 lb dumbbell = 12.5 lbs, 2 * 1.25 lbs on 15 lb dumbbell = 17.5 lbs). I sometimes even stick 'em on my 20 lb dumbbells for double arm rows or deadlifts if the reps aren't too high and I'm feeling energetic.
I also have 2.5 lb ones which I mostly use for kettlebell "grind" exercises (e.g. deadlifts) -- I wouldn't want to do something dynamic like a swing and have a heavy chunk of stuff flying across the room! My foot, kids, furniture and windows thank me for exercising caution
And finally, I have weighted gloves that go up to 2 lbs and I've set 'em at 1.5 lbs. I don't use 'em as frequently unless I'm doing something with high reps for shoulders where 5 lbs is too light and 8 lbs is too heavy -- the perfect in-between for a 6.5 lb dumbbell! Fiddling with them between moves is a bit annoying and slows me down/causes me to pause the routine more often than when I'm using Platemates (where I still occasionally have to pause stuff if the transitions are fast and I can't use the same set of weights when moving from back to chest, biceps to triceps, anything else to shoulders).
That being said, I was about to purchase a 14 kg kettlebell to round out my collection right before the pandemic hit and I can't believe how hard it is to get one now! It's literally the last thing I want to add to my inventory... even if I dream of a dumbbell set that could replace the 12.5 lb, 17.5 lb and 22.5 lb combos I create with Platemates so I can worry even less about the time needed to switch weights