A lot of cognitive science now recognises a phenomenon related to the Ebbinghaus Forgetting Curve. You try something, nearly get it...but not quite. You try it another time....nearly get it.....rest. Then you try it....and it sits right there. Cog Scientists call it spaced practise - it is better to practise something ion separate chunks at different times rather than doing a 6 hour block.
https://www.mindtools.com/a9wjrjw/ebbinghauss-forgetting-curve