Some fifteen years ago, Shuler formulated three conjectures relating t
o the large-time asymptotic properties of a nearest-neighbor random wa
lk on Z2 that is allowed to make horizontal steps everywhere but verti
cal steps only on a random fraction of the columns. We give a proof of
his conjectures for the situation where the column distribution is st
ationary and satisfies a certain mixing condition. We also prove a str
ong form of scaling to anisotropic Brownian motion as well as a local
limit theorem. The main ingredient of the proofs is a large-deviation
estimate for the number of visits to a random set made by a simple ran
dom walk on Z. We briefly discuss extensions to higher dimension and t
o other types of random walk.