If it's a style you've brewed a lot already I'm betting you can get pretty close on all marks from the memory of past brewing sessions.
I think this will help you to see the effects of your brewing techniques as compared to depending on measurement crutches. Use your senses to find your marks. (Zen brewing ) "Be the beer Grasshopper!"
That is why I think I can do this....I have brewed so many 1.050 beers with 10 lbs. of malt, be it pilsners, APAs, best bitter, weizens, etc., that I think I can do this in my sleep.
The sound of the water heating up, and the look of it (gassy, from the flame hitting the bottom of the kettle) has me guessing the strike temperature about +/- 5° when I subsequently meaure it. It has emboldened me to do this.
Think I will do an APA...seems like I could just add handfuls of C-hops near the end of the boil, and it will turn out okay.