I came across this sentence in a video where a real lawyer reacts to a popular TV series about a lawyer. He said it about a scene where the prosecutor shows the jury a video of the deed instead of a closing argument. The scene speaks for itself ("res ipsa loquitur"). There's no sugar coating or making it worse by talking about it. So, "to gild the lily" means "to embellish or improve something unnecessarily". This idiom goes back to a misquotation of Shakespeare's play King John: ""To gild refined gold, to paint the lily". Actually, "to paint the lily" would be the correct quote and both expressions "to paint/gild the lily" were both used for some time. Interestingly, "to paint the lily" is outdated now, while "to gild the lily" is still in use. I couldn't find anything on "to pound the rubble", so I'm not sure if this is even a common idiom or some metaphor made up by the speaker on the go. I think it means that you don't need to further pulverise something that's already broken into tiny pieces. I find it interesting that the verb "to pound" has several meanings. Here it means "to crush to pieces, to pulverise". I was only familiar with the meaning of "beating something violently" like "pounding at the door", or striking something repeatedly, like "pound the table". "Pound the table" can also be used figuratively with the meaning "to assert one's position". We have a similar expression in German: "mit der Faust auf den Tisch schlagen". But "to pound" can also mean "to walk". When you "pound the pavement", you're walking the streets to accomplish something. Someone who's looking for a job or campaining for a cause is "pounding the pavement". I find it interesting, how much you can learn just from one sentence.

Question to the native English speakers: How common are the mentioned expressions? Does "to pound the rubble" exist as an idiom?

Question to English learners: Do you have similar expressions in your native languages?