However, if you are hiring someone to do design, you should confirm what your expectations are for the design process. For instance where I work, the first phase is a creative design phase. This would end with parameters on which the schematic design would work with. The schematic design would take these parameters and do several options (we do usually do 3). The creative development is important so that the schematic design can start to narrow some options. Since we do WAG/Rom Budgets and rough sketches during this period, having a decent idea of direction is necessary.
The end of the final design phase is an important point - at this point the design should be able to be very specific. If you are doing the design and build, perhaps this isn't as much of an issue - except that you will undoubtedly have scope creep, and lose money. If you are sending the final design out to be bid, the design package has to be done in such a way that your bids will come back and provide you with an apples to apples comparison.
A colleague, Chris Wilson, a Project Manager for a local museum stalks about the RFPs & the Scope of work:
Scope of Work (or Scope of Service) – assume nothing.
This is where RFP’s live and die. 99 percent of your effort should be spent on this section. This is the place for any and all information that might be relevant to the fabricator. Assume nothing. Leave nothing to chance.
Stick with me for a minute:
Imagine that you want a cookie. You call 6 bakeries and tell them that you would like a price for a cookie. You get six prices that are wildly divergent. You realize that you should have been more specific. You stipulate chocolate chip. Still the prices are all over the map. In separate conversations you stipulate size, type of flour, etc… Eventually, you have told the (now annoyed) bakeries (in a very tortured, drawn out process which, by the way, is not documented anywhere) the following information:
I would like one (1) chocolate chip cookie between 5 and 5.5 inches in diameter, containing no less than one heaping tablespoon of semi-sweet chocolate morsels. The cookie shall have a slightly gooey texture, but shall have sufficient tensile strength to be self supporting if lifted from one end only. No trans fats shall be used as part of the ingredients of this cookie, and it shall not be processed on any machinery that comes in contact with peanuts, or any other kind of nut. The cookie shall be delivered within the next 24 hours, in packaging that does not require the use of any tools to open.
Now, of course you would never buy a cookie in this way, because it is a far more intuitive process than building an exhibit. And because there is a cultural understanding of what is in a typical cookie.
I simply use this as an example of how you will never get what you want unless you ask for it.
This is why the Scope of Work, and especially the TECHNICAL exhibit descriptions are so important in an RFP. Depending on the characteristics of the exhibit you are building, the descriptions can be as important as the drawings.
Bringing that back to the sandwhich, unless the size and number of bacon/tomato slices are noted as well as the type of bread and such are documented, you may still find differences. One shop might use a high sodium bacon, because it is more economical. Another might use a high quuaility one, but less of it. A third shop might want to use turkey bacon because they have some left from a different recipe. While a shop might be able to save you money (value engineer) or increase the value (value added) you want this information to be clear so that there are no surprises. "Oh you wanted extra mayo - thats extra $$...."