Always keep an eye on file sizes. The goal is to achieve optimized balance between smallest file size and maximum output sharpness and clarity. Achieve that balance first, outside of InDesign, so the issue is settled before you bring it into InDesign. Because you are dealing with printing, you will also need to target the final image ‘physical dimensions’ into the mix also (you wouldn’t need to do this for web work where dimensions are always pixels and not inches.)
The file you place in ID should 100%.
I always (95% or the time) place a same size image. That would include covers or interior page layouts.
When I place oversize images its usually for things like logos in ads or a single image in a story where I can’t be bothered to make it smaller.
The main thing is to not make the pre-press department scream at you.
You want to place the image at 100% at full resolution of your output device. If you enlarge the image in In Design, you run the risk of down sizing files upon the creation of a PDF to lower then what is acceptable resolution. So in essence if you are shipping these PDF’s off to publications and you place the image larger then 100% in the layout, you may get an e-mail or phone call with the file bouncing. In Design DOES NOT resample images.
Also – Clipping paths are resolution dependant which many do not know. If you place a high res image in In Design at lets say 14%, your path WILL explode once it hits the output RIP.
Other things like PDF check-up will fail as well as other automated checking systems if you monkey around with sloppy handy works.
