In a magazine you always have a combination of spreads and single pages for separate topics. In a InDesign document you can't work with a combination of spreads and single pages.

In order to print a PDF by an offset printer, 3 mm bleed is required all around a page. Further it is required that all the pages in the PDF are exported as single pages with bleed and crop marks. This works fine for a spread that has one big image that overlaps both pages of a spread. But not for a spread that has an seperate page layout for the left and right page (because they have different topics). Then you can't have a correct bleed for the images that lie against the inside of the page edge. InDesign is using the part of the image on the other page in the bleed! See screenshot. It is not possible to fix this by changing the layer order.

The solution is simple: InDesign must show the bleed between the pages of a spread and fill the bleed correctly when exporting to an PDF if you choose to export as single pages with bleed and show crop marks. Or it must be possible to mix spreads en single pages in a InDesign document.