I've had and worked in a lot of 3 series husqys over the years. Ony ever had one screw fall out of the 390xp, 394xp had the muffler come loose/loose a nut once. Never had an issue with the 346xp, many 350's, the 359,562xp, 365, 385xp etc. Logging buddy has been using 372xp's since they came out up to about 5 years ago. Can't remember him complaining about loosing screwes. (Don't mean he didn't, just I can't recall it, and I do most his saw work for him.) Worse saw I've ever had for screws coming out is the flipping muffler on the stihl 192tc. Finally got to the point where I had to heli coil it and stick nord lock washers under each screw.
Not saying my experiences are the end all be all by any means, but I certainly haven't seen the screw just falling out of 3 series like some have reported over the years.