Last night while I was writing I noticed something insidious: a hidden adverb! We’ve all heard that weak writing relies on adverbs. We’ve all caught ourselves writing about a character “breathing quickly” only to ask ourselves, in near panic, What’s a single verb that means breathing quickly? So imagine my surprise when I reread the following sentence:
As rainwater poured in sheets off the roof beside them…
Poured is decent verb for rain. And “in sheets” helps describe how the rain is—hey, wait a minute! I’m modifying my verb with…duh duh dumm…a hidden adverb! Okay, it’s not technically an adverb, but it’s doing the same work: slowing down my readers and letting me get away with weaker verbs. My solution?
As rainwater sheeted off the roof beside them…
Jacobsen Writing 
A good point. One of the only counters to the general rule I can offer is that sometimes ridding words can detract from the rhythm and tempo of the sentence. In that case, you’re left balancing the lower word count and impact against the flow.
Also, although this may be rarer, in your case above. The sound-alike and spelling of the verb sheeted when read aloud in my mind came across as the rain shitted off the roof. I paused after making this mental slip of the tongue and then asked myself “How does rain sheet off a roof?” Like a billowing sheet? A constant stream? So sometimes the modifiers add necessary clarity.
Thanks for the words, Joshua. Good food for thought. I hope to get back to that story in the next few days, and I’ll let you know what I settle on…or if I still need help! I like your idea of reading it aloud different ways. Now, how about, “The rained pillow-cased off the roof sheetily…” That makes things a lot better, eh?
Why can’t you just let me forget about them? Now I’m going to worry my words are slowing down my readers and that will slow down my writing.
Ross, you have permission to use every word. Now keep writing!