Multi-Field Review Site or Single Review Site?

Hey Guys,

Currently, I have four sites, one for technology, one for travel, one for sports etc. All of these sites are reviews sites and essentially do the same thing.
Should I keep four going or just pick the best domain and focus on one huge review site with decent category separation on the topics?

Separately, they all do below average. I'm just wondering if I should instead focus on one site properly instead of 1/4 assing 4 sites.

Choose any one domain first and work on that site.
After the success of that domain you can continue with other domains because at the same time you can't concentrate on all domains.

I agree with Owanceaser. Pick one and once you have mastered this, you can branch out.

I'm currently doing a double setup with mine in that I've got a full on review site for different niches and also got a site solely in niche X. Both are doing pretty damn well actually, but it's taken quite a while to get them both up to a great standard.
I'd recommend that you follow the silo guide that @splishsplash wrote, it'll definitely help.