They usually do, yes, but the actual importance of incline and decline pressing changes depending on your goals. If you want a huge flat bench, you spend most of your time doing the flat bench, using incline and decline to address certain weaknesses and to add variety to prevent overtraining a specific movement pattern.
If your goal is general fitness, you can alternate between them all, pretty much choosing whichever you want to do on a day. If your goal is a specific physique, you'd pick whichever variation addresses a specific aesthetic goal.
Sounds like your goal is basically general strength, you want to get stronger all around without a specific push towards huge numbers on the flat bench. I'd rotate them around, then, spending about 3 or 4 weeks doing each in turn.