Why increase pointer by two while finding loop in linked list, why not 3,4,5?

Question

I had a look at question already which talk about algorithm to find loop in a linked list. I have read Floyd\'s cycle-finding algorithm solution, mentioned at lot of places

Answer 1

If there is a loop (of n nodes), then once a pointer has entered the loop it will remain there forever; so we can move forward in time until both pointers are in the loop. From here on the pointers can be represented by integers modulo n with initial values a and b. The condition for them to meet after t steps is then

a+t≡b+2t mod n which has solution t=a−b mod n.

This will work so long as the difference between the speeds shares no prime factors with n.

Reference https://math.stackexchange.com/questions/412876/proof-of-the-2-pointer-method-for-finding-a-linked-list-loop

The single restriction on speeds is that their difference should be co-prime with the loop's length.