Affect of Shipping Settings Automation on sales?

Morning All

I am wondering if anyone can advise if turning on SSA has any affect of your sales volume? I turned it on a maybe 2 or 3 years ago, I think when it was launched, and it had a negative affect on sales because the estimated delivery time became a lot longer than on my normal shipping template and customers were not going for it.

I had a call from an Amazon rep a couple of weeks ago to to ask if there was a reason I wasn't using it and they told me that I wouldn't have the same problem if I tried again but I am not convinced.

So just wondering if anyone that uses it can advise what affect it had if any? My sales have fallen through the floor since April, presumabely due to this algorithm change and I am trying to find way to improve things!!

I don't do SFP.

Thanks