Why simple cut of finger of several millimeters takes several days to fully cure? why not several seconds?

Are cells that are cut (muscle cell could be 10 cm long written in wikipedia) could recover as one again or do they become two or both ends do not survive?
Is cleaning the wound of damaged tissue takes so long? (maybe medical tools can help then)
Or generation of inter-cell matter?
How long it takes for (say muscle) cell to duplicate (or it's from stem cells that fill-in the gap?)?
Maybe we can make cut very smooth so that only one/several layers of cells be needed to cure the cut? Or is it usually already so for say sharp knife?

Is curing in mainly done during sleep by the body?

Any other potential areas to improve curing speed?

Thank you!

see
https://en.wikipedia.org/wiki/Wound_healing

you will see that the damaged and dead cells in the dermis and epidermis are cleared and then new cells replace them. That takes days to weeks depending on the amount of damage that has occurred. Regeneration occurs day and night though many other factors will affect the rate of healing some of which may have diurnal rhythm to them.