Neither wrong nor right - just different working areas and different size frames.
Probably the quickest technique to achieve what you want:
1. Layout > Margins and Columns > Gutter: set the size you want the gap between your photos to be.
2. Select Rectangle Frame Tool, start drawing a rectangle from the upper left corner, where you want block of images to begin.
3. While drawing (don't release the mouse!) hit Right Arrow key once and Up Arrow key 3 times.
4. You'll get 2x4 'live' graphic frames under your mouse.
5. Still holding the mouse left button pressed, finish drawing frames to the bottom right corner of your working area (or where you want it to end).
6. Release the mouse.
That's all! A lot faster to do then describe.
Hint: if you don't want to touch default gutters setting or changed your mind while drawing, you can adjust the width of the gaps between frames with Alt+Arrow keys (while you still hold the mouse button pressed!).
Just experiment couple of times and you get use it soon.
winterm's answer is one correct way.
Another way to recreate the layout on a new page is to copy the page in the Pages panel menu, then replace each picture with the new images. If you want the layouts to be identical, this might be easier.
Right, and even more: if you want the layouts to be truly identical, and you have more than a few such pages, you should consider bothering with a special Master page - with graphic placeholders
My proposed approach is handy, when layouts differ a bit from page to page, say, you may want 3x4, on another page - 2x5 images, etc.
Thank you so much!! Exactly what I needed. I am most grateful for your help!