My module essays are about 3/4 based around my essays I wrote for the assessments.
I'd say I spent about 30 hours on each one of them.
At the moment I'm in the process of writing one definitive essay for each module, integrating past work and a bit of new, I'd say it comes to about 35 hours each (I.e. 30 +5)
Once I've done them, I'll read them daily (or more often) and my general outline of themes, techniques etc. for each for about a week. By then it'll be about 4 weeks to the hsc and I'll begin writing essays to 40 minute limits.
so 35 hours, then 40 mins