Hopefully this is clear. I want to send a person a project. It has a simple 2 keyframe animation. One is a mask property, the other a slider property on the Stroke Effect. I want a way to have the person adjust the final timing of the animation by only inputting the amount of seconds they want it to be. So for example if they want it to be 5 seconds, they would input 5 into a slider on an adjustment layer and the 2nd keyframe for the mask and the slider would adjust accordingly.
So basically I want a control for the length of the animation. If that's even possible.