What Michal said is on point. Other points to consider:

1. Total number of targets. Fragmented is what you want, but if there's (as an extreme example) only 5 companies in that industry then you really don't want to try to roll up that industry.

2. A superior operating model that can be easily and quickly transplanted into each acquired company is critical. It will often help increase the barrier of entry as you grow, scale, and acquire more and more companies.

3. You want a large multiples arbitrage. If you can acquire the companies at 3-4x and exit at 13x then that's a great amount of arbitrage worthy of consideration

4. The product/service should be frequently used/recurring. Flooring companies, for example, are not an ideal industry because every client is serviced once and doesn't need to be seen again for 10 years.. If not more!

Overall, a roll-up is both a financial and operating play and can't be treated as one or the other.

Happy to chat anytime to discuss in more detail!

I can not talk about the specific case of Australia, because I don't know it. But I would say that, if you are looking for an industry with roll up potential, first I would try to understand the microeconomics of why an industry is transitioning from fragmented to consolidated (is it maturity of the industry, sinergies, changes in consumer demand towards a few players). Also, I would draw an strategy as to why/how can you execute a roll up strategy, have you found a way to create sinergies by creating a platform of similar companies? Are you going to integrate vertically or horizontally?...