Very applicable all the time. Any time any object in you environment moves, it's behavior adheres almost perfectly to Newton's laws. You may not able to record enough of an environment's factors (e.g. air resistance, friction) to make an accurate prediction, but the system is still acting in a Newtonian way (momentum transfer between individual air molecules and a moving object is Newtonian) and usually you can use a simplified model to be mostly accurate. Much of modern engineering is based on the application of Newtonian Physics.
But Newton's model is still slightly inaccurate, because it doesn't include Einsteinian relativity. However, the two models only diverge significantly at extremes: high velocity, high gravity, large distances, and so on. For the majority of applications the differences between the two are negligible.
>Is it completely false or are there some concepts which can be used to accurately predict real-life situations?
"Completely false" and "can be used to accurately predict real-life situations" are not mutually exclusive. Newtonian physics is, when you get down to it, a false model of the universe. However it's very *close* to being right at the scales we normally care about, so it's okay.
It's like using "3.14159265359" exactly as the definition of pi. It's completely false, but at the same time it'll usually be good enough.
If you assume the relative velocities involved are 'small' then the equations that govern Newtonian Physics fall out of the ones that govern general relativity.
Realistically the everyday world is mostly low energy. We can calculate the difference between the two theories but the difference is usually less than we could measure, and almost always small enough that it's unimportant.
Just about every object around you, with the exception of electronic devices, was designed using Newtonian physics. Cars, skyscrapers, houses, furniture, airplanes...
Quantum mechanics is needed to understand semiconductors and the chemical and mechanical properties of materials, and relativity is relevant in a few specialized devices, but otherwise, the world is built on Newton's laws.