Perhaps 40 and 45 hours choices are not distinguishable in the real world. 9-5 or 9-6? 8.30 to 6.30? All of these can be equalized with some decompression time

Perhaps 40 and 45 hours choices are not distinguishable in the real world. 9-5 or 9-6? 8.30 to 6.30? All of these can be equalized with some decompression time during the day. The real problems start when these windows are non-viable and 50 hours+ is numerically when that starts happening.