Uses of 正好 / zhènghăo
正好 is not an adjective, the same as 'just right' is not an adjective.

正 shows a foot, stopping at a line or wall. = right, proper
好 shows a woman and a son. Apparently to indicate a good life. This was before the 21st century! Today, this may not be considered the only way to fulfillment!

just = "exactly, precisely, punctually, not more than"
good = "excellent, fine; valuable; desirable, favorable, beneficial; full, entire, complete, pleasing;" 

这个饭正好
This dish is exactly fine/complete.
正好下雪
punctually favourable snow was falling
正好20人
exactly (the) desirable 20 people
我们正好一起去吧
we exactly (mutually) beneficial go together
我正好没有什么人主张
I precisely (the) desirable don't have anyone to make decisions for me 

Of course, I would not translate the Chinese into English quite like this. I just want to indicate what is going on. 

Both 正 and 好 have more than one interpretation, in English as well as in Chinese. So when you mix them, permutations of meaning arise. There is no "one size fits all".

What Dan said: 正好我们可以整理一下你的光盘。

或者： 我们正好可以同时整理你的光盘。