One frame would basically be 1 render. 24 frames per second = 240 frames for a 10 second animation. That's 240 renders. L&P has bought a computer for this task alone (according to him), and it's equipped with 2x 3090ti's with NVLink, so a single frame is rendered within a couple minutes and in some cases even seconds depending on the scene, not hours. lol
L&P's animations should only take a couple hours of render time. Difficult to say how long exactly, but considering a single 3090ti can render a 3min short at 24fps with 4320 frames (which is used for Benchmarks) within ~25 hours using Blender, you can be very certain that it's not taking him weeks or months to render a couple short animations, especially since he's using two linked GPU's.
Now, the RTX 4090 can be up to twice as fast compared to a single 3090ti in certain scenarios, but for L&P's purposes I'd say it'd be a waste of money. Could be worth it for his animations, but even that is very questionable as he's not creating movies or shortfilms. It's only a couple second long animations for the most part.