There's an extremely useful technique called tap wari or off tap. On paper, this means you unhook the sheet you're drawing on from the holes that connect it to a pegboard (also called a tap) and slide it around over the others to match up different parts of a drawing as precise guides. This lets you keep difficult areas, like faces, on model by overlapping the faces between drawings even when the character is moving across the page. It's also used to measure the arc between keyframes by rotating different cels to find an arc.
Digitally, it's exactly the same except much less annoying. If you're working in Clip Studio or similar animation software, the light table function even lets you slide drawings temporarily then snap them back.
You can slide, rotate, and do anything else you need off tap. Need to match a leg bent in a run to the previous (straight) leg? Slide the new drawing to match it up, then snap it back. Want to double-check the eyes aren't getting squished as they move? Untap and check. Digitally, you can do quick checks like this with parts of a drawing, too – you can draw a head over the previous frames, then lasso it and drag it to match up with the next frame of movement. Whatever works!
Tap wari also helpful when preserving volume between drawings is important, or when you just want to double-check how the next frame you've drawn matches up to the previous. It becomes progressively more important as the animation makes its way down the pipeline.By the time a cut hits douga, volume and proportion from frame to frame is everything and tap wari is used constantly.
Now, let me give a word of warning: focus on keyframes first. If you get bogged down trying to figure out spacing charts for inbetweens before you're happy with how your keyframes are working, you'll almost certainly end up having to redo timing and spacing anyways.