Yes, each character update will be roughly 10 minutes worth of content. I did the math this morning and let's assume each girls still have 50 minutes worth of content to be completed, it would take me 3 years to complete de game, but I'm confident to get it done within 2 years. For example, the 0.02 release expand Patty's story and I get it done in 3 weeks only. The last 0.03 release, I introduced Ophelia, expand Trishka's story and it took me 4 weeks. (Regarding Trishka's story, there will be another 50 minutes worth of content, I do not count the intro when the MC met her.) For the next 0.04 release, this one will be dedicated to Astrid only, the same is likely true for next two girls remaining. All the update depends on how much free time I have available in a week really.
It's hard to tell how much time a major update will take at the moment, but I guess it will take a little more time than a character update, however, I will still target the 4 - 6 weeks time frame for the major one.
Like I said before, I'm completely transparant about this game development. You can expect at least one minor / major update every 4 - 6 weeks from now on. Delays could happen and if it's the case, I take a few minutes to make a post about it.