Globally, most military troops have an empty chamber in a weapon unless and until they are actually under live fire conditions. That is likely why the safety on the MN is what it is: it probably wasn't used much if any. You will like the M39. The carbine version of the MN was for support troops, artillery, etc. They likely never used them much in combat but still needed a weapon if called upon. The majority of Soviet infantry doctrine revolved around the automatic weapons, organic artillery such as mortars, and for close-in; the PPSh. These weapons and tactics with a combined arms approach - maneuver warfare with armor, heavy artillery and rockets, plus air power when available - is what wins battles. The bolt action rifle sounds cool but its effects on the battlefield historically speaking, were minor.
See the German experience: they also had the squad and platoon firepower mainly depend on the machine gun. Their bolt action 98k was not the decisive arm of battle. Once they encountered the massive firepower of the PPSh during close in engagements, the Germans being smart did not reinvent the wheel (if it works, use it!). They used the PPSh concept themselves. They also developed the assault rifle concept; hence, the StG series.