The defendant has a right to a speedy trial. This means they can make the entire trial happen on a particular time span which I do not know what it is. I may be wrong in this next one, but if they exercise that right and it doesn’t happen they win the case with prejudice. Meaning they cant be tried again for the same crime.

I had this explained to me a long while back.

The attorney said “we should waive speedy trial. This judge hates when defendants do this and it usually goes poorly for them when they do”. So I waived.

I suspect with how busy the courts, the prosecutors and the defending attorney all are every case gets waived these days.

It's just a check so that the courts can't jail you almost indefinitely while they prepare.