The pattern every 5 points might relate to the torsion structure or the fact that 5 is a factor in the curve's properties. This is only true for the curve over real numbers - in secp256k1 (mod p), all coordinates are reduced modulo p.
This has no bearing on the security or behavior of the actual secp256k1 curve used in cryptocurrencies, where all operations are performed modulo p. The size of x-coordinates in the real number curve doesn't affect the cryptographic security.   


what do you mean by "the fact that 5 is a factor in the curve's properties" how is 5 a factor ?