I'm trying to keep my bullet journal fairly simple, but darker marker on one page can show through enough to put me off writing on the back. Then I end up skipping pages, which feels daft when the whole point is to use the notebook. I can't decide whether to just live with it or keep those pens to one side.
No need to retire them completely. Keeping the darker markers to small headers or accents instead of big filled areas leaves more of the reverse usable.