I spent a lot of time in Northern Ireland where we often moved around covertly in a wide variety of military tasks, where civvies and unmarked cars were the norm. I carried a Browning Hi-Power during one tour and then a SIG P226; having tried most different kinds of holster I always prefered a standard or high ride holster on my right hip (3 o'clock) and the magazine holder (with 2 spare mags) on the opposite side at 10 o'clock.
The nice thing about having your holster at 3 o'clock is that it stays put whether you are getting in and out of a car, or are walking around a lot. That way I always knew where my pistol would be and muscle memory took my hand straight to it every time. Simarily the magazines are in the same place, so when I reload I don't have to think about where the magazines are - they stay in the same place each time.
When you need your weapon in a hurry, the last thing you need is to fumble around for it.
Also your arm over the holster helps to conceal it and retain it in a crowded place, as it will prevent a member of the public bumping into you and realising that you are carrying.
I'm bemused by the suggestion that items of clothing or anything should induce a negligent discharge when you reholster; the only thing that makes a pistol go off is your finger on the trigger! Anyone who isn't reholstering with their finger outside the trigger guard, pointing down the frame, is badly trained and looking for somewhere to have an accident.
Firearms safety isn't about external factors. It's all about properly trained people who are careful and know what they are doing; forget all the safety features on your weapon, forget about grip safety, the thing that makes it to 'bang' is your finger squeezing the trigger.
That index finger is the ultimate safety device and 'you' control it.