Are there more return award seats vs oneway?

Paying cash, there is normally more availability or lower costs booking return flights vs two direct flights. Does it work the same way with award seats, or is availability (particularly with Qantas, JAL, Virgin AU) the same?

Reason I’m asking is I’m looking at a 2 month trip Melbourne to Tokyo say 1 Dec to 1 Feb. Knowing this is a peak travel time waiting for the 1 Feb space to be available to book, likely the 1 Dec will be well and truly snapped up. So I could book these flights separately - will that increase my chances of award seats both ways?

In general, I’d say there is no difference in availability between the two. A more critical aspect is, you are more likely to lose the first flight if you wait 2 months for the second flight. In short, I’d book them separately as I’d rather secure flights when available.