If using a biner block, its very simple to install redundancy as well: just clip the karabiner into the bolt using a sling and 2 karabiners, a chain of karabiners (not ideal) or (best case) a dedicated quickdraw (canyoners carry dedicated quickdraws with lockers on for this reason). Then there's no need to worry about which side gets loaded. Really basic canyoning technique which many cavers don't seem to know about.
Ian is correct, you really want to use a triact karabiner for biner blocks. Means there's no need to worry about anything coming undone.
Its still a good idea for the last person down to be experienced in pull-thrpough SRT; they can also supervise at the pitch head.
Of course its best practice for a pullthrough to be tested before the last person descends, and this is quite feasible if using a biner block as well, especially in caves as opposed to canyons where white water can cause ropes to get very twisted if both ends hang down the pitch. However if a biner block is used I would estimate you will have very few issues with stuck ropes in a caving context, I certainly never have. Every single stuck rope I have had in caves has been due to clipping a knot to the rope, which I stopped doing after learning some basic canyoning techniques in New Zealand and then in the Alps. Knot clipped to rope is an outdated technique which is unnecessary and has been shown to cause problems.