Rental Market Over Saturation

[Eddie Torres]

Hello all. I was just curious on what sort of research and/or tools do you use to determine if a market is oversaturated with property rentals. I've seen an area with an average of 90 days on market before being leased which would be laughable compared to the bay area in California where places get rented almost immediately. But I realize that all markets are different. How do some of you experienced investors approach this?