This would work properly only when the private key of P is zero mod 32. P=k*G, k=0 (mod 32).
Otherwise the point is guaranteed to not be in the interval.
The probability of being in the new interval is 1/32, which is about 3%. In all other 97% the algorithm would fail to find a point in any reasonable time.
If you somehow can deterministically move points from bigger interval to smaller, then no kangaroos are needed, ECDLP is solved. In the 1/32 case - in just 8 steps (!!!).
No, it is not like you say:
if you know that P lies in [1G,100G]
then you know that 2P lies in [2G,4G...,400G]
and that kP lies in [kG, k2G, k3G, ..., k100G]
that remains true even if k is inv(2), inv(3) and so on.