Thanks for sharing Erika, and yes I agree with you. I never charge per second. It is mostly common in traditional animation.
Sometimes I charge fixed price for a bundle of animations. If those are described very detailed. And I know the customer for a while. Since some customers just do a lot of back and forth while changing the original requirement. In case of fixed price I estimate the price or agree on their budget. A year ago I took a cartoon project where each scene was fixed 60€(simple scenes with humans making facial emotions with 3d head shearing), I didnt know what scene will come next, easy or super hard so I was praying before opening PSD

. So I prefer hourly rate.
I work with different client with a different hourly rates. it depends when I started to work with them. Normally if I start with that rate I dont change it. So it varies between 10€ - 30€ per hour.
I can use some kind of software to track my hours. A software that provides the client, or if I work on Upwork I will use their native tracker. but mostly clients trust me which allows me to track my time with my phone and report daily(to avoid any surprises later). I never track time spent chatting or on meetings.