If you could give one bit of advice to someone?

[Slick]

So the question remains, what if you had this many leftover resources at the end of a turn and every ship/cnstruction yard in your empire is building ships of the baseship and larger size?

Then, in a nutshell, you have too few spaceyards. You should be scrapping a facility on every planet that doesn't have a spaceyard to build one. And you should't be building baseships, you should be building Spaceyard Bases to add even more spaceyards.