Is it me or is Riot a bit slow on updating champions gameplay wise?

I'm not saying their reworks are bad or anything, but they are very slow to release them.

I can understand taking a long time for the likes of Sion and Poppy, but champs that require smaller GPU seem to take forever to get released, or have a huge gap of time if they screw up(see Skarner waiting MONTHS to get the new stun passive).

Before you say it takes a while to find the right kit, it shouldn't take months to find a kit that works better/is healthier for the champ, unless they have to code it into the game each time they decide to test a kit which will take much longer to finish.

Some champs don't need huge gameplay updates, just some functionality changes on skills or changing the skill entirely(see how Ashe got a new passive and new Q) I don't see how that can take months to do, even with changing numbers to balance it.

What I'm really trying to get at is that champs that require smaller updates shouldn't take such a long time to be updated(like Ashe).

"But it takes longer to make sure it's good for the game!"

Yea it took a while for the Rengar rework, and that is great to be assassinated slightly slower than before the rework, am I right?