Its petty but its not a waste of time because it will not get considered for a vote. Nothing is going to happen on impeachment until Mueller is finished. Even then, absent a smoking gun, there will be hearings about it and more investigation.
What did Nixon in is that there was in fact a smoking gun.
I am more and more convinced that ultimately Trump will lose reelection before the impeachment conclusion is reached. He might be indicted in New York afterwards. But unless there are direct communications between Trump, or someone expressly at his direction, with Russian officials then second and third hand proxies leave too much room for Trump to convince his base he can wriggle out of it.