If you read into this discussion by not starting off the nosing you're likely to have problems with alignment. For example, it's almost impossible to distinguish what the installed measurement will be with 15 courses/rows of 3" wide plank (example)
The math comes out to 45 inches (15 rows x 3 inches) but depending on the product quality and how it's installed there's likely to be what I call a gain. The measurement may become 45 3/8" once installed. What you want to avoid is being off at the stairs if the flooring is running paralell. Imagine what it would look like with a 3/8" sliver or fill piece. Then if the squareness if off you may have some areas tapered from 1/8" to 3/8" as an example. Trust me it's very diffucult to get that kind of piece cut to fit perfect without looking like a botched job
The math comes out to 45 inches (15 rows x 3 inches) but depending on the product quality and how it's installed there's likely to be what I call a gain. The measurement may become 45 3/8" once installed. What you want to avoid is being off at the stairs if the flooring is running paralell. Imagine what it would look like with a 3/8" sliver or fill piece. Then if the squareness if off you may have some areas tapered from 1/8" to 3/8" as an example. Trust me it's very diffucult to get that kind of piece cut to fit perfect without looking like a botched job