Additional flour threshold: when and how to perform?
Adding more flour to a bread recipe until it looses stickiness is a mistake many inexperienced bread bakers make, and one I made myself. Dough recipes have a hydration level, which is a way of expressing the amount of water in comparison to flour by weight. A higher hydration level gives a more open texture with bigger holes, lower hydration gives a more dense loaf with smaller holes and a tighter crumb. High hydration doughs are stickier and looser than low hydration doughs, and it's nothing to worry about. Ciabatta is a great example of a very high hydration dough that is essentially a floury puddle, and that's normal for that recipe.
Recipes have a hydration level, if you add more flour than the recipe calls for you will reduce the hydration and you'll end up with a denser loaf. If you keep adding flour until it can't absorb anymore you'll get a barely edible brick. My focaccia recipe is very sticky and runny, but if I added more flour to it I'd ruin it.
I'm not saying I never add a sprinkle of flour to my bread if it's a bit too sticky or loose, but it's rare. If you are getting bad or inconsistent results I would try these things before adding more flour:

Weigh everything, including the water, in grams. My baking never got consistent until I measured by weight instead of volume, because you can never get exact with volume measurements. I convert all my recipes to metric, it's a minor one-time effort that takes the guesswork out of things. 10 grams of water is 10ml, i.e. two teaspoons. It may not sound like much but it can make a difference in a dough, and chances are you won't be able to tell 100ml from 110ml in a measuring cup. Weighing water lets you get the right amount of hydration
Take notes, if you follow a recipe and it still is a bit wet then take a note to lower the water content by 10-15 grams next time. Once you find the right balance note that too
Make sure you are using the right type of flour for the recipe. Bread flours contain more of the proteins that form gluten, and gluten formation absorbs water. If you are using lower protein flour it will absorb less water. If plain flour is all you can get ahold of then it will still make bread, you will need a bit less water. Course flours absorb less water than fine flour, so if you are using a coarse whole wheat in place of a finer flour you will need to adjust the recipe
Control the water, not the flour. If you have a recipe you suspect may have too much hydration it's better to withhold some of the water and add it in later if it's needed rather than adding it all and needing to add more flour. This way you keep the balance of flour(s), salt and yeast right
Remember that the purpose of kneading is to hydrate the dough and ensure a thorough distribution of the ingredients. Gluten forms naturally, helped by yeast, kneading doesn't develop gluten, it just gets it there faster by pushing all the water around. So when you start there will be a lot of unabsorbed water, and it will be sticky. This is natural, you just need to keep working the dough
Also remember that rising changes the dough structure through yeast action and gluten development, so a dough that is a bit loose and sticky may firm up after a rise
Kneading technique may make a difference, you may just need to do it a bit longer

So, before you think about adding more flour be aware of the result you are trying to get, and keep the above in mind.