Can exhaust fans lose umph over time?

[Waltermelon]

I push air through mine, no problems yet. I know, I know. The book says... maybe running a smaller filter at a higher cfm is different?

 

[PuravidaC]

I push air through mine too because I don't have space inside grow room. In hindsight I should have put a pre-filter at exhaust intake but now have new, larger fan and filter. Just another learning step along the growers path!