This is a question I've had before too. I think guidelines tend to be most used in primary care settings when there is a clear, researched answer to a problem like which ethnic groups respond best to which anti-hypertensive, metformin in early DM2, or surveillance screening for colonoscopy. With psychiatry, since, technically, many treatments aren't more efficacious than other, people are less inclined to follow guidelines, but instead do their own thing or practice how their programs teach them.
That said, there are actually quite a few guidelines. There are the textbooks of course, but there are also guidelines addressing particular treatment options for particular diagnoses. However, these guidelines are mainly international, focusing in Canada, Europe and Asia. I'm sure there are others in the US, but I don't come across them often when I've searched for this.
For bipolar disorder, for instance, I found the guidelines belowin the citations of an article I read. I try to combine international guidelines with the practices of my residency to find a nice middle ground, since most medical thought differs regionally.
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Grunze H, Vieta E, Goodwin G, Bowden C, Licht RW, Moller HJ, Kasper S. The World Federation of Societies of Biological Psychiatry (WFSBP) Guidelines for the Biological Treatment of Bipolar Disorders: update 2009 on the treatment of bipolar depression. World J Biol Psychiatry. 2010
Nivoli AM, Colom F, Murru A, Pacchiarotti I, Castro-Loli P, González-Pinto A, Fountoulakis KN, Vieta E. New treatment guidelines for acute bipolar depression: a systematic review. J Affect Disord. 2011;129:14–26.
Yatham LN, Kennedy SH, Parikh SV, Schaffer A, Beaulieu S, Alda M, O’Donovan C, Macqueen G, McIntyre RS, Sharma V, Ravindran A, Young LT, Milev R, Bond DJ, Frey BN, Goldstein BI, Lafer B, Birmaher B, Ha K, Nolen WA, Berk M. Canadian Network for Mood and Anxiety Treatments (CANMAT) and International Society for Bipolar Disorders (ISBD) collaborative update of CANMAT guidelines for the management of patients with bipolar disorder: update 2013. Bipolar Disord. 2013;15(1):1–44.
Goodwin GM and Consensus Group of the British Association for Psychopharmacology. Evidence-based guidelines for treating bipolar disorder: revised second edition—recommendations from the British Association for Psychopharmacology. J Psychopharmacol. 2009
NICE Clinical Guidelines. Bipolar disorder. The management of bipolar disorder in adults, children and adolescents, in primary and secondary care. National Institute for Health and Clinical Excellence, 2009.