If you see something that should be done differently, you need to make the case from the start that people who don't install these things do not and cannot know what the space and other requirements are. Then, you should at least push back, even if your pressure doesn't end up in a brawl. You can include such things as... (some of these examples are from the past, but that doesn't mean the same kind of thing can't happen again) --

sometimes new equipment requires more space than what's needed now (might need to add a PC in the space, for instance);

completely unforeseen changes, apparently out of left field, might require drastic or impossible changes later (might need to remove the 50' Component cable you put in, then later remove the spiffy new HDMI cable you replaced it with and put in a different one, so you should have had conduit);

display advances might totally change the required display space or shape (such as when we went from 4:3 RPTVs to 16:9 TVs, which made ALL 4:3 spaces the wrong size);

the construction company runs, say, one RG6 to each TV when that is almost the completely wrong thing to do....

Don't ignore these past changes and how hard they were to accommodate. Stuff like this will happen again. Plus ça change, plus ça change pas: The more things change, the more things don't change. Realize that things that can't be planned for will happen and try not to get stuck with less than what you need now. It will only get worse.