Getting within 5% of the bottom is only marginally easier than picking the bottom itself.
We can each look for signs and adjust our financial situations accordingly, but there's no real way of picking the bottom or even getting within 5% of it.
Of course, we'd all rather buy in at 5% off bottom than 10%. That goes without saying. But how can we pick 5% off the bottom when we can't pick the bottom?
The other factor is picking the real bottom over the nominal bottom. If prices bottom then stagnate for 5 years, the nominal bottom is the same for the entirety of the 5 years whilst, barring a deflationary environment, prices have declined for a further 5 years in real terms. Given that Melbourne's atrocious yields rarely cover holding costs and the unlikelihood of rents tripling within 5 years, it's more desirable to buy in year 5 than in year 1, though this isn't reflected in the official (nominal) bottom.
My point is, depending on the situation, even if we could somehow know when we've hit bottom, it doesn't necessarily mean it's the best time to buy. Like picking the bottom, picking the best time to invest requires hindsight.