Yes not a fun day
Now if I get a crack and it’s not too bad I use crazy glue to seal the crack
If it’s a deep crack I put plastic skin in the crack let dry and apply the crazy glue. This was recommended by my rheumatologist

I must say, we do have some colourful nails around here, toenails and fingernails included. Those of us who have toenails or fingernails . We don't even need polish as our actual nails have spots, stripes vertical and horizonal and all sorts of neat stuff.
Polish is nice though, painted or stick-on. Hides all kinds of problems and we sure have a lot of them so it seems.

Mine are coloured blocks in strips of horizontal lines

Problems with cracks and breaking with fingernails and big toenails. I don't do nail polish on fingernails as that dries the nails out and makes the problem worse. I highly recommend press on fake nails as I find that protects the nails so they grow, don't break and stay healthy. Self adhesive press on nails, not glue as that dries nails and damages them further.
Toenail polish, in summer, works for me. But I give toenail polish a long break in winter when no one sees my toes anyway. My big toenails have major ugliness issues.

not in the middle but my nails are brittle and chip and break. I do think that is a symptom of getting older also