How have courts interpreted the Sixth Amendment in the context of pleading guilty?

(Ginns v. Savage (1964) 61 Cal.2d 520, 524, fn. 2 [cases are not authority for propositions not considered].) Instead, Tovar held that the Sixth Amendment does not require the court to specifically advise a defendant who wishes to plead guilty on two points: (1) that waiving his right to counsel entails the risk that a viable defense will be overlooked, or (2) that, by waiving his right to counsel, the defendant will lose the opportunity to obtain an independent opinion of counsel on whether it is wise to plead guilty. (Tovar, supra, 541 U.S. at p. 81.) No such "rigid and detailed" admonishments are necessary, in every case, to ensure that the defendant's counsel waiver is knowing and intelligent. (Id. at pp. 91-92.) "In prescribing scripted admonitions and holding them necessary in every guilty plea instance," the lower court "gave insufficient consideration" to the high court's "guiding decisions" and "overlooked" its observations that "the information a defendant must have to waive counsel intelligently will 'depend, in each case, upon the particular facts and circumstances surrounding that case.'" (Id. at p. 92.) The advisements at issue in Tovar were unwarranted under the facts and circumstances of the case, in part because Tovar "never claimed that he did not fully understand the charge or the range of punishment for the crime prior to pleading guilty." (Ibid.)