One suggestion, it's much better practice to connect LEDs in series first, and connect those series strings in parallel.

Reason for this is LEDs Vf variance, if you connect multiple LEDs in parallel, current distribution could be unequal, LED with lowest Vf will draw highest current, and because of that if will become hotter, and Vf would drop even more, current would rise even more.. etc. I've seen this problem in LED T8 tube light, shadows and bright spots were visible because of unequal current distribution and measurements confirmed that.

With 3 (or more) LEDs connected in series first, all strings would have total Vf closer to average (more leds - more equal average total Vf among strings because of probability laws).