The Supreme Court in R. v. Rodgerson, 2015 SCC 38 says jury charges are too long - see below. Some might suggest the Court is responsible for the great increase in length of jury charges because of the complexity the Court often adds to previously simple matters (say the principled approach):
3) The Role of the Trial Judge
 While the Crown and defence counsel both have roles to play, the role of the trial judge is the most vital, and the most difficult, in formulating jury instructions. A trial judge must strike a crucial balance by crafting a jury charge that is both comprehensive and comprehensible. Recognizing the difficulty inherent in this task, this Court has "repeatedly endorsed" the functional approach to reviewing jury charges (R. v. Mack, 2014 SCC 58,  3 S.C.R. 3, at para. 49). This functional approach is designed to "ensure that the yardstick by which we measure the fitness of a [jury charge] does not become overly onerous", in order to reduce "the proliferation of very lengthy charges in which judges often quote large extracts from appellate decisions simply to safeguard verdicts from appeal" (Jacquard, at para. 1). Under the functional approach, the trial judge's duty is to "decant and simplify" (ibid., at para. 13). Over-charging is just as incompatible with this duty as is under-charging.
 More than 15 years later, the concern expressed in Jacquard remains. However, rather than quoting large extracts from appellate decisions, trial judges have taken to quoting large extracts from model charge manuals to safeguard their verdicts from appeal. This has resulted in an overreliance on the rote reproduction of excerpts from model jury instructions. But model charge manuals do not necessarily translate into model charges. They are a tool, not the final product. They are there to guide, not govern. In my view, the failure to isolate the critical issues in a case and tailor the charge to them inevitably makes the instructions less helpful to the jury and adds unnecessarily to their length and complexity.
 Courts have repeatedly emphasized that the jury charge must "be tailored to the facts of the specific case" (R. v. McNeil (2006), 84 O.R. (3d) 125 (C.A.), at para. 21). While "[t]he model instructions are intended to provide a starting point for trial judges", modification will frequently be required to provide the jury "with the applicable legal principles in a format that facilitates the application of those principles to the specific circumstances of the case" (ibid.). Trial judges must "separate the wheat from the chaff" when determining which defences may be applicable, and must engage in a "careful and considered culling . . . to avoid unnecessary, inappropriate and irrelevant legal instruction of a kind that might well divert the jury's attention" from the primary disputed issues in the case (Pintar, at p. 494).
 This principle was endorsed in Helping Jurors Understand (2007), at p. 82, by no less authority than Justice Watt of the Ontario Court of Appeal (then of the Superior Court of Justice), also the author of the Ontario Specimen Jury Instructions(Criminal) (2003):
A specimen is a sample. A specimen instruction is a sample instruction about its subject-matter. Specimen instructions do not and cannot be expected to provide legally accurate directions for every set of circumstances that fall within their reach. There are no one-size-fits-all jury instructions. At best, specimen instructions provide the basic building blocks for finals and other instructions. The twists and turns of individual cases will dictate the nature and extent of modification required to ensure legal accuracy. [Emphasis in original.]
 In the present case, a few modest alterations would have saved this jury charge from legal error. At the same time, a great many of the instructions that were included could and should have been removed. In the event that Mr. Rodgerson's new trial adduces substantially similar evidence, and the positions of the parties on that evidence remain the same, it is my view that a substantially more streamlined jury charge would suffice. Mr. Rodgerson would benefit from a jury keenly focused on the evidence and arguments forming the basis of his defence, and not distracted by hours of confusing and repetitive generic instruction. The Crown would also benefit from a simplified charge, with fewer unnecessary contours in which grounds for an appeal of conviction may lay hidden. I do not wish to appear naïve, and I recognize that such an everybody-wins approach is easier said than done. Nevertheless, I remain firmly of the view that "common sense and the law need not be strangers", and that the fundamental purpose of the jury charge must be "to educate, not complicate" (R. v. Zebedee (2006), 81 O.R. (3d) 583 (C.A.), at para. 82).