Like in Duik (Rainbox https://vimeo.com/225599368) you can time remapping a bunch of keyframes in One properties effects. Kbar (compatibility)
One Morpher create a Null layer with a slider wich time remap your select keyframes on other layers.
Morpher can be really useful for adjusting the speed and interpolation of many properties at once. It can do this with one simple value graph. It even works for properties that have two and three dimensions.
Shift + click: Name your Slider not automatically
Open Source script