F Major Question-Aaron Shearer scale studies

[salzo]

Have been working in the Aaron Shearer scale study book and just started the Fmajor section. I am wondering which finger should be used when playing the D on the second string. The third finger seems the most comfortable until I get to the broken chord and thirds studies- In those studies,he says to use the 4th finger for the D, and the third finger for the Bb. He does not give any finger designation for the other studies.
I am wondering if the fourth finger on the D should be the "standard" finger that I should use when playing in F major. I realize there are always exceptions with respect to which finger goes where, but I am thinking the 3rd finger D should be the exception, and the fourth should be the norm. I would appreciate any advice, comments, direction, etc.