Because the time stone didn't allow him to travel in time, only to manipulate the time and see the future.

You should also add, that Superman is used to having superpowers on earth, and his enemies are overflowing with new sensations coming from all the powers the yellow sun gives them and are confused and unable to fully use their powers.

@coner I believe there is a derogatory term for everything, every race, nation, city-population, and so on. It is bad to be from China? Then why are they called Chinks? Why are Jews called Kikes? Why Yankees? etc. etc.

The only thing always mentioned is that Gary Oldman had to learn an "American Accent" and did it so well, he forgot his own english accent and had to learn it again after the movie. I have never seen any specific accent mentioned.

Or just the awareness of autism, asperger's and other disorders was too small back then, and maybe even the writers have never heard of them and only knew of ADD, since that was the most often diagnosed disorder in kids in schools.

Probably a bigger budget after the success of season 1 was the reason. I have no source, this is just my guess based on logic.

@user207421 why?

@BrettFromLA but this could be a tradition that started a while ago, before digital cameras and software

Maybe if the editor is searching for the place to prepare to cut and is fast-forwarding the shot, he will notice the tilt and stop the playback and will end up exactly at the spot before the clap. Without the clap, he would have to reverse the footage after noticing the shot has started. This could have been tricky to reverse in analog editing.