In my opinion, the "Layer -> First Layer Settings -> First Layer Width" setting doesn't do what it should, in fact I would go so far as to say it has the opposite effect in terms of improving print quality or adhesion. My opinion is based on observing the effect of increasing the value and the resultant effect on first layer print quality.
The "Tool Tip" text states: The width of the first layer extrusion can be increased to help with adhesion
My interpretation is that increasing the "First Layer Width" should only affect material flow rate to produce a wider than normal first layer traces. It may do that but is also changes (reduces) the number of computed infill traces resulting a greater probability of poor coverage (gaps) in the first layer. IT SHOULD NOT AFFECT THE NUMBER OF INFILL TRACES!
I am wondering if anyone else has noticed this and concurs that this behavior is unacceptable.