In my textbooks, youtube videos, different websites, I have seen that during calculations regarding interference of waves we derive the equations in such a way as if there is no distribution of energy by waves., I mean if it is a circular wave then the diameter of locus wavefronts will increase witth the passage of time by indulging more and more particles and involving new particles has to be done by distributing energy(as far as I know). So shouldn't this cause change in amplitude as time passes? Moreover aren't each wavefronts subject to countless interferences causing it to distort largely from its initial form?
An intuitive approach will be much more helpful. Thank you.