I've got 4 girls chugging along in a 4x2x5 tent. Two are 66 days old (Girl Scout Cookie & Diesel Cookies), two are 48 days old (Girl Scout Cookie & Purple Rolex V2).
Got my 3x3x6 tent yesterday, so i'm in the process of swapping out. Some wasted space in the 4x2 (4' leaves a small gap in the middle). The 3x3 will maximize my 4 plant setup, plus i'm gaining an extra foot of head space. The hydroton pebbles have increased plant size greatly, my second GSC is going going to end up about 15-20 inches taller than the first one that doesn't have hydroton pebbles.