A question I've never directly posed, waiting for the answer to become apparent over time (still a relative newcomer), is whether there are conventions regarding body text sizing in whole or perhaps half point size increments? In book layouts, I typically find myself using the work of others as a template, and the point size of the body sometimes appears to be in half increments or even something odder than quarter point size increments. Do my eyes deceive, and do most designers/typsetters adhere to standardized sizings for body text (10, 11, 12 pt)? At present, I'm tempted to set something in 11.25 pt. Dante.
do most designers/typsetters adhere to standardized sizings for body text
No. The majority of designers are going to consider aesthetics factors such as: font used, the visual space the text will fill, reader demographic, the theme or conceptual feel of the piece, etc. to determine an appropriate size, not limiting themselves to a nice practical point size. One thing to consider, once a point size has been determined for your layout, a paragraph/character style should be created, and if you choose a quarter point size, you won't be entering 10.876 in the text panel. Personally, I don't worry about odd point sizes, but will round off leading values (14pt instead of 14.357).
Nothing wrong with using fractional point sizes, but I think traditionally only whole points would have been used -- I doubt many foundries would have produced metal type in any thing but whole sizes.
Some of your thoughts that you are looking at fractional sizes in other's work may simply be the fonts in use -- there is a wide variety of x-height and ascender/descender lengths among different faces, so not all 10 pt type seems to be the same size.