They are very strong. I used one for one week on a wee heavy and its way over the top. A year later its still overpowering. I used it again on another batch, not as bad but still too strong.
Last batch is a lambic where I cut the spiral in 4, alternated soaks in about 8 refreshed baths of boiling water. Hope it won't overpower but i will have bug inoculated spiral piece
My recommendation, cut it, boil it and check the beer after the first day and go from there