Hi, when should I consider taking the hive entrance out? It seems very congested on sunnier/ warmer days. What do others do?
The entrance block/reducers don't give a standard size 'reduced' entrance. So, what works for some reducers (and bees) won't work for all.
A small and orderly queue at the entrance isn't a bad thing.
When it gets to be a seething scrum, the opening is possibly too small. This usually happens when the bees are exploiting a large nectar 'flow' - such as from OSR at the moment.
In late summer and autumn, when wasps (and potentially bees for other hives) are intent on robbing, a really small entrance becomes necessary.
A small colony should always have a small entrance.
A personal opinion of mine (not in the books) is that giving the bees an overlarge entrance to defend makes them over-defensive, attacking anyone that moves anywhere near their hive. Smaller entrance, fewer guard bees, entrance-way full of bees, much less trouble for and thus from the bees.
Entrance blocks are quite easily made from cheap B&Q (for example) stripwood.
So, you can make a few with different-sized openings at very little cost.
Last point - a low entrance, no more than 6 or 7mm tall, should perform perfectly well as a mouseguard, without needing a metal grid over it.