I'm shooting in all natural or available light so there are no complicated lighting setups to deal with. How much time do you think this saves me?
This really depends. On an overcast day, it's going to save time, but then on an overcast day, I'd be wanting my Gaffer to grab some pocket pars and things so it isn't
so goddamned flat!
On a sunny day, it could slow you down, because you may start shooting in sun, only to find that the sun goes behind the clouds for another 15 minutes, or you start shooting in the morning overcast conditions, and then the sun comes out and the second half of the scene doesn't match with the first half, unless you start pulling out and rigging big scrims and diff frames.
You'll need to really carefully plan your days, times of day and all the rest of it if you want it to look good. And you're always the whim of the weather - even if you're inside and shooting a scene where sun's pouring through the window, but turns out it's a cold, rainy, overcast day, or simply that by the time you go to shoot there, the sun's moved on. Your options are: put up a light, put off the scene until another day when the sun
is pouring through the window, or shoot it anyway and just accept that it's not going to be anything like what you want.
There's 16 shoot days scheduled for a low budget indie drama romance feature. Without going too much into specifics, does that sound doable to you?
Yeah, it's certainly doable, but it all depends on who's in your crew, how many in your crew, how experienced and professional your crew is, how long your shoot days are, where your locations are, how long your scenes are, what the weather's like, etc. etc. etc.