Bad advice eh? I wonder why you should be treating hives with no appreciable varroa loading? They are out there, you know.
If there is little infestation left when you do your thymol treatment, and sometimes little before that, why subject the bees to an unecessary 'medication' or 'hive cleanser' only a few beeding cycles later. I think I only have a couple of colonies which are likely to receive an oxalic acid treatment. The rest will have far less than the accepted harmful mite threshold. Your bland comment of 'if you see any mite at all you should be treating' is, frankly, rubbish. Perhaps you were one of the beekeepers who hastened the resistance to the miticide strips, like apistan, by treating for far too long and treating mites with a sub-lethal dosage.
Whatever treatment you give for varroah control, there will be survivors or reinfestation. FACT OF LIFE. Newcomers may read your post and think what you said is the way to go. NO IT IS NOT. If that were the case everyone who has a keen eye would be 'treating' most of the year! Oh yes, we should all be treating all the year, but selectively, as and when necessary. It's called IPM.
Why treat with a further chemical, which may affect spring build-up of the colony, if it simply does not need it? I am not a commercial beekeeper, and as such can monitor and treat each of my colonies on a rather more than 'blanket 'strategy.
Furthermore, your comment 'is only an indication of how many have dropped in the last half hour or so ' is also utter rubbish. Anyone with a modicum of common sense will know that. Speak up now, if there is anyone else out there that would do a mite drop count lasting only half an hour or so!
As far as I am concerned oxalic acid poses no threat to me. I have used it for more years than varroa has been around in the UK, probably twice as long.
If some are not entirely happy then don't use it. Be safe.
And I haven't got to F's yet.
RAB