Nope, I don't have premium. (and just checked, my girl with 110 max takes exactly 5 hours to go to full, so 120 max (both momentos) would presumably be only ~5:30)
and yeah, 2x4 and 1x2 is what I used.
(also, 4 hours for 30 (7.5 per hour) is better than 6 hours for 50. (8.3 per hour). Point was not only is 6 hours for 50 less efficient as the prior poster said, but you can't even get the full benefit of the 6 hours.