The followthrough on a fade, as you contact the inside of the ball, is more across the back of the ball with wrist at a different angle. The followthrough on a hook is up the outside of the ball, like the classic "salute" that everyone says as a simplification of the followthrough. Straight topspin and hook can be very close to the same stroke but for straight topspin you come more over the top of the ball instead of up the outside of the ball.
If I straight topspin down the line, it works okay. If I hook, down the line, if the ball hits the side-line, it still ends up 2/3 of the way to the center of the table by the time it is one foot past the end-line, which defeats the purpose of the down the line shot. Whereas, with inside-out sidespin (fade sidespin) it gives more room for error because, if I land the ball a foot inside the side-line, by the time it is one foot past the end-line it is still outside the side-line.
For reference about the differences between cross-court and down the line stroke form, or the form of the FH stroke if you are hitting from the BH corner to the opponent's BH corner, watch Wang Liqin and look at his followthrough from BH side and from FH side.
Many of the fundamentals are the same. But the followthrough and how you use the body do change.
The best way to sort that out is to practice, practice, practice, which is what brokenball at the top.
When you have done the stroke enough, all you do is think about where you want the ball to land. If you are thinking about more than that, in the middle of a pressure situation, it will cause problems. But you need to practice the shot enough to get to that point where you only have to think about where you want to place the ball.