Whiteboard animations are a relatively quick and easy way to communicate high-level concepts and I always have a lot of fun making them.
I generally write the scripts myself, which are then signed off by either SMEs or the client (or both). I record the voiceover (usually me) and draw custom illustration assets for the video.
Below is the animation I created for Mero to advertise HARE (Holidays Act Remediation Engine):
A whiteboard animation can take anywhere between a week to 21 days to complete; this is entirely dependent on getting the script 100% correct and signed off before beginning work on the assets.