Ive tried to grow big ones before too. Ive spent days caring for a jar, wrapped in layers of insulation, gradually stepping down the coldness. This was put in the cabinet overnight and BAM there they were without even trying. my guess is the heptane was so saturated that it didn't need the cold.
Here's the sad part, big thick crystals don't seem to want to melt/burn correctly in my GVG so I ground them all into a fine powder.
"It may be that my role in the universe is, to question my role in the universe."