In cases like this, the benefit of separate one way tickets is that you can change or cancel one direction without affecting the other.

As we know, you can't just skip/cancel the outbound without the return getting cancelled.

For example, OP books Thurs out, Monday back. Suppose Wednesday morning, the "come right away" phone call comes. OP still wants to come home Monday. Now we need a same day ticket for the outbound. Maybe at that point, a new one-way ticket might be cheaper than re-ticketing the entire thing, since the re-ticketing would likely put the return into a full-Y basis too. Or maybe another airline becomes a better option for the outbound, either because of price or schedule. With two one-ways, OP books a new outbound and keeps the original return.

I agree with others, if the chance that you'll want to change both legs (say, to a whole different weekend) is greater than the chance you want to change outbound only, then a single ticket is the better option.

And I agree that an award ticket is ideal, if you have the miles, especially if it's a high-frequency route likely to have award seats on surrounding days.