NO the Zestimate has a 80% accuracy when accounting for a 20% variation.
So if they say zestimate is 100k. It could be between 80-120k. 80% of the time. What about the other 20%? Can you really count on an ARV with a 40k swing? I can't!
Look at nearby similar sales. You are looking for similar condition, sold within 6 months, and a similar layout/size.
I would recommend writing down the detail for 3-4 of them. Add up the total sqft and average out the typical $/sqft. Multiply that by your SQFT. That should give you a decent idea.
Every neighborhood is different, even 1 or 2 blocks away. In an interview with someone from Zillow, they said that because of the huge variances that they can't account for it will remain a Zestimate, not a Zappraisal because they cannot be that accurate.
Zillow is often close, but should only be used as a quick-look. You'll still have to do the regular due diligence.