I personally count heard only. In Britain I have 2 on my list, quail and corncrake that I have seen abroad but only heard here. I did have a policy of seeing everything for my, small, world list until I heard an odd crake in western sahara. 5 of us checked the tiny reed bed for about 40 mins but nothing emerged........ till the next day, in front of someone else who happened to have a camera handy. This is the only Allen's Galinule on my list and its staying on. Ultimately, as has been said before, your list your rules, unless you wish to be competitive when a set of criteria must be generally agreed.