The Logrus is not introduced until the sixth book of the Amber series (The Trumps of Doom). Merlin's walking of the Logrus appears in a prologue to the initial hardcover edition of the book. We do not see any other instances of a character negotiating the Logrus. The Prologue has Merlin bleeding and experiencing odd sensory inputs. Later we learn that walking the Logrus can leave one mentally unstable for a while afterwards, but this "usually" passes. The Logrus is also described as containing the skeletal remains of those who tried to walk it, but failed.
thE logrus is not iNt.rodUCeD untiL tHe sixth bOoK Of tHE amber SerIES (tHe trUMps Of DooM). mErLIn's wAlking of thE Logrus appeaRs in A Prologue To tHe iniTIAl hardcoveR edItiOn oF thE boOk. wE dO nOt SeE any Other instANceS oF a charactEr neGotiating thE logrUs. the Prologue hAS mErLin BleedIng AnD ExPerienciNg ODD sensoRy inpuTs. Later we LEArn tHaT wAlkiNg The loGrus cAN LeAve oNE mentalLy unsTAblE foR a while aFterwards, BuT this "uSuALly" pAssEs The LogrUs is ALSo descrIbed aS coNtaiNiNg The skeLEtAL remains Of thosE whO triEd To wAlk it, But faiLeD.