Longer than a typical 1004, double the work and you must verify the other appraiser work as well as complete your own. Even though the form does not have locations for your conclusions of market stability and over supply etc. It must be done.
A day or longer depending on where the property is located in my service area. It truly is more work than completing an appraisal on the property, you have to have some understanding of the methods of the appraiser to understand the appraisal. Then to be done properly you have to re-verify all the information in the appraisal you are reviewing.
The additional scope of work of adding two additional comparables also increases the fee.
Then, if you disagree with the opinion of value you have to go ahead and complete an appraisal of the property yourself.
That's why my fees are quite high for this type of work and why I don't always get the assignments.
verifying data, an hour or two. Everything else you mentioned (additional comps, value recommendations etc....) is an appraisal. I do desk reviews. I do appraisals. I do not incorporate the two into a single form as per some AMC directive. Needless to say, I do not do many reviews these days.
This is really a question that involves the scope of work. If you are on staff with a lender and their scope is reduced significantly, it may not take you too long to do these and may not include verification of certain data. See what exactly the scope is before making a decision. Ask other people who do what you are thinking of doing because the answers you might receive here could be likening delivering a Caddy versus a Yugo when all your client wants is a Yugo (both get you from point A to point B).
It depends on the SOW which would also include the format you will communicate your results in. What is the purpose of the review? Is it a quality control function or is it something else? How will you report the results, in a narrative or on a form? What type of certifications and limiting conditions will you be making?
There are no answers as to how much time it would take. Some can be done very quickly and others open Pandora's box. I generally take a quick look at the report and its data and if it appears like it's going to be the box then don't hesitate to renegotiate the fee or turn the assignment down.