Are you sure that this is true for the Netherlands in general?
You will know better than me of course, but I would be very surprised if all cachers who do not find the log sheet call it a day and refrain from logging found it logs.
The situation might change if the cachers realize that finding the log sheet is part of the challenge, but this often is not the case and then what I described previously happens quite easily. If you label the cache as mystery, you will be better off than with the traditional label as for traditionals you need to expect that about 50% of the visitors do not read the description.
Cezanne
That sounds a good plan i will make at a mystery. And will state in a form the finding of the logsheet is the difficult part.
Maybe i will put in a wee note stating to find the logsheet. Then even for those not reading the description will read it on the spot.