You could use full CD accesories, then use SSJ, Kid Buu or GN and your transformation cooldown will be less. I remember taking it down to 45 min in old DBO.
Having full cooldown equipment + Martial Artist cooldown buff in DBO KR meant I could go SSJ every 14 minutes. Cooldown got nerfed since. ;~;
What's more important is how useful the transformation is when you're actually using it. It doesn't matter how much ENG you have, you don't regenerate enough EP in combat to keep up fights for long, so you'll end up wasting time sitting around recovering you could've otherwise used to keep fighting. The stat boosts are minimal, and since you can't use better buffs like Kaioken or Thunder in SSJ form either, it's mostly just for toying around.