Drowning Infantry Swimming onto Land?

As everyone knows, this can be done.

However, sometimes the drowning infantry can make it to land and sometimes they cannot.

When can drowning infantry swim to land and when are they unable to?

P.S. Please inform me if this is a bug. As of now I am assuming that it is a feature.

It is because the land is close enough for the range to tick in, I'm almost certain it is when the land is within the 1 unit range (could be wrong about number, but around there) value. When it exceeds this it will fail to reach land, in HTML 5 the range is even more precise, because in SL there were ranges with putting a transport in the middle of UK and France as a bridge, but that is harder to do because as I stated its more precise.

Overall not a bug, it's just a mechanic that works like the range glitch, where you can push units to their max potential by zooming out slightly, infact I have noticed zooming out can help for this too if its not allowing you to move units to land, but its a much more delicate thing to do with the limit mobility.