There are numerous investigations. No one said thousands but it’s certainly more than one. Problem is, they are complex and some are intertwined.
Any unnecessary chatter and exposure on the part of investigators in one investigation may screw up successful prosecution of this or that actor on a technicality [remember that Bill Ayers the Weather Underground bomber was guilty as heck but got off on a technicality] and the screw up may not be limited to just the immediate case but in related cases, or leaks and chest thumping may alert as yet unknown conspirators that someone close to them has been flipped or discovered and cause the unknown actors to destroy evidence or flee.
The safest thing if an AGs thinks his job is to pursue and eventually prosecute these leads is to keep his mouth shut and that of everyone on the prosecution side. If he has no interest in prosecution, then he can leak about his investigation like crazy, as did Comey. The drawback is if there is no leaking, and no one’s tooting their own horn, a proper investigator is going to be thrashed by all the folks who are accustomed to Bush and Obama era leaks and ant more.
The Hezbollah-cartel-drugs-immigration thing is exactly what Sessions was brought on board to tackle, not the political sideshow that is the Mueller investigation that no one could have predicted was going to be carried to such extremes.
In a way it’s a blessing that so many flaming libs are tied up in that or else they would be meddling in these other investigations and leaking, but it is frustrating.
Comey admitted he leaked information. He did this on the record. why is he not charged? It has been over 6 months. What are they waiting for?
Why are Strzok and Page and Ohr still in the DOJ? They are not vital to anything. They can destroy evidence.
You are correct in that the AG should be silent until his work is completed. That does not mean he should let the suspects die of OLD AGE while all are waiting.