Recently I was watching luggage handlers loading luggage into my plane at Amsterdam Schiphol while I was queueing to board (20-30 minutes before takeoff). There was a female luggage handler who started unloading a luggage-cart train starting form the last cart. She was very slow and would pick up only smaller pieces. I suppose she was waiting for males to help her with the heavier ones. Smaller as well as soft pieces were actually stacked on top of the carts while the massive hardcases would lie at the bottom of the carts. Clearly some sorting must have been done while loading (which was reassuring since I was traveling with a soft backpack). As I didn't see my luggage there, I suppose it had already been loaded (I had a 2.5h transfer at Schiphol). However, at the luggage reclaim I got my luggage quite quickly. Interestingly, I met a traveller who had exactly the same flights as me and when I was leaving the airport he was still waiting for his piece. One of differences was - I had a backpack while he had a regular suitcase.
My point is, I saw only a small part of the whole process, yet there was plenty of room for scrambling the order. It is mostly manual work done by a number of individuals and I guess that makes it pretty unpredictable.
As for the backpacks - I mentioned that as I came across several airports where they have separate bag drops for backpacks with loose straps so I assume there might be different ways of handling these. However, I haven't noticed or heard of any (dis)advantages of having this type of luggage.
Finally, I kind of accepted that it is a pure chance when I reclaim my luggage and I usually try to do a little trick. I just get busy with various things between the landing and reclaiming the luggage. During that time I tidy up my hand luggage, change clothes when going to warmer/colder places, tidy up my wallet - replacing currencies, preparing bus tickets etc., go to bathroom to refresh myself, be it makeup or brushing my teeth, also, after a long flight it is nice to do some stretching. Playing with the phone is fine too - change a SIM card, maybe look for a socket to charge it a bit. After completing all these things I approach a baggage reclaim place full of impatient people waiting there already for ages. For me it is only the beginning of waiting and typically I get my luggage within a few minutes and my nerves are saved.