I do not believe there is a single answer to this question. Circumstances vary from market area to market area. I rarely adjust for lot size but I might adjust for site utility.....size is just one component of utility. For example: two waterfront lots may have the same total size but one might have significantly more water frontage. Additionally, the one with less frontage may have a sandy beach while the other has rocky shoals. Those adjustments, or lack thereof, would be under SITE. However, if one of the lots were adjacent to a mobile home park and the other was among homes similar to the one under comparision, then you would have a location adjustment.
It is interesting and helpful to look at new tracts of homes and see if there is a price difference between model matches based on site size. In my market area there is no value difference if both lots are standard size. By standard, I mean what would normally be considered a full size lot. However, if the project is in a PUD of deatached homes on tiny sites, there would be considerable difference in value for even as little as 500 square feet. I once did the bulk of all the appraisals in a tract where many of the lots were along a gentle slope. Going up the slope, adjacent lots were no more than 2 feet difference in elevation. However, the homes became increasingly more expensive (for model matches) with each step in the elevation. There was not a view amenity in the classical sense. However, the higher UP the slope the more one couled look DOWN ON his neighbors. While I adjusted for VIEW, I explained that the market accepted the higher prices as SNOB APPEAL.
It is interesting and helpful to look at new tracts of homes and see if there is a price difference between model matches based on site size. In my market area there is no value difference if both lots are standard size. By standard, I mean what would normally be considered a full size lot. However, if the project is in a PUD of deatached homes on tiny sites, there would be considerable difference in value for even as little as 500 square feet. I once did the bulk of all the appraisals in a tract where many of the lots were along a gentle slope. Going up the slope, adjacent lots were no more than 2 feet difference in elevation. However, the homes became increasingly more expensive (for model matches) with each step in the elevation. There was not a view amenity in the classical sense. However, the higher UP the slope the more one couled look DOWN ON his neighbors. While I adjusted for VIEW, I explained that the market accepted the higher prices as SNOB APPEAL.