Love these kind of ideas, Henry Cook and I managed 600 species in a day in GM a few years ago and for nearly all we weren't using optics (it was a plant race and we found 500 species - we weren't targeting other things). I honestly think with enough planning and luck you could see 1000 species in a day in GM (and thats without going into beetles, spiders etc).
"birding without optics" we used to call it "going for a walk"...
Did this on Wednesday evening walking to the pub along the Mersey and was delighted to observe an active Sand Martin colony and various other riverside delights
My point was an ultimate riposte (unstated) to the new breed of birder who never even looks at anything that isn't digitally rendered on the back of a tiny screen attached to a hugely expensive and hugely heavy zoom lens whose optics are vastly inferior to bins or scopes. These are the people who grew up watching wildlife only on TV and never twisted a forked twig into spiders webs in a hedge or hatched a caterpillar or experienced any sort of wildlife for REAL in the REAL world. Read Chris Packham and Robert Macfarlane on the subject.
Sorry Tim, but I am already off on a a bit of a tangent - has anybody else heard of 'birding by stats'? I know someone told me about this years and years ago, but I and a student have looked for anything about it on the internet without any joy. The idea is you don't even bother with the ID, you just go out looking until you have seen 100 feathered things, and by stats you will have seen 20 blackbirds, 12 wood pigeons, 9 BHGs. etc...
back on topic, 'Whiting' sounds like a great idea to hone your skills. As a bit of a crap birder, the birds I would probably struggle with most would be waders. What about other people?
I just had an idea for a challenge: how many species can you ID in a day if you go the Gilbert White road and leave ALL your gear at home? Anyone up for it?