I'm getting mixed feedback on whether you have to approach publishers/agents one at a time (giving them as long as it takes to respond), or whether a bigger hit is now regarded as inevitable,even acceptable. I certainly don't want to annoy a possible agent or publisher but I'm also baffled as to why writers have put up with this unreasonable requirement for so long.

It might seem annoying but it's purely so they don't make you an offer and then find that you've had one elsewhere- and then they could end up in a bidding war which gets very, very expensive for them. There are other reasons but this is definitely one.

When you submit material, ask them if they have an exclusive policy or not, and why. At least you'll know then. Best of luck.

Thanks Anna; the very mention of a bidding war is music to my ears....unlikely as it may be... but I can see the drawbacks for them. Nevertheless, this can only work for the writer if turnaround is speedy which, from what I've read on WW, it isn't.