I always played it by ear, I do watch the weight, but I don't get overly analytical about it.
My bike weighs 32 pounds, and my gear and food weigh a total of 28 pounds sometimes 30, plus just over a pound of water. I carry more water than most because I problems with kidney stones, so I have to drink more than others to keep me flushed, since I upped my water intake, I went from having 6 or 7 stones in 5 years to none in the last 10 years, so yes, I take more water than most. Some places I go into I may not have a water source, so before going into those areas I will fill my bottles I drank from while riding at a mini mart or fast-food place, so every bottle is full. Getting a kidney stone while touring would not be good!
When I first started doing this stuff, I had a very strict budget to prevent me from over buying crap I would find out later I didn't need, but it also meant I had to buy some stuff that was heavier than I would have liked. Since then whenever I had to replace something, I looked for lighter stuff. The other thing though you have to be mindful about is that a lot of the lightest weight stuff will cost you a lot more money, but the durability goes down, you have to be constantly thinking when replacing something to lose weight, or buying something for the first time and you want it ultralight is the durability factor of that product. The other issue is you can find something that might save you half a fourth of an ounce, but will cost 4 times more than that "heavier" brand, is that worth the money then? I don't think so, but some people who are gram counters will think it's worth it.