What is the usability of the Colebrook, Haaland, and Swamee equations in engineering work and the need or not to tailor the equation selection i.e. will Haaland always work or in some circumstance should a different equation be used? What about the iterative Colebrook vs. the explicit Haaland? Is it better to iterate or just get a direct albeit more inaccurate (maybe?) friction factor from Haaland? etc.