Second that! Multiple lights are always better especially working with a bigger space like 4x4 or 5x5 in your case. If you spend a little money you can get 2 really good leds to fit that space with good results, if you op for cheaper Leds id say you need 3 maybe 4 depending on the coverage and a par output.
I think 4 would give great results it's just which lights to chose from, my advice is do a bit if research and get the most efficient available....I see a lot of people using a lot of energy with LEDs in small spaces, I've seen 1000w of I think Mars of Vipar in a 5x5.....that's a lot.