The previous Lubavitcher Rebbe, Rabbi Yosef Yitzchak Schneersohn related the following about the time that is referred to as the “heel of Moshiach.[1]”
One clearly sees that although a hat that is too small is not unbearable to wear, a shoe that is too small crushes the feet—becoming insufferable.
It is therefore understood, that the Almighty need not be to exacting in regards to the time of the heel.
[1] Otzar Pisgamei Chabad. Vol. 1. Pg. 407