Fatigue Effect: This seemed to do nothing to the
performance
of the CPU but had a slight effect on human controlled players. Mainly a placebo slider
Fatigue Recovery: Both sides fatigue levels went down on Max but recovered very quickly, this however appeared to have little effect on the game but perhaps in a more positive way. It did not impact ice time as it was distributed from line 1 to 4 as you would expect to see in real life. so again could have been listed in sliders that have no impact as it was tough to discern if anything changed as a result of this.
Unless I missed it, you didn't mention whether you used manual or auto line changes. I use hybrid control which means no choice but auto. The reason I ask, at some point I noticed that all 4 lines on my team were getting the same ice time, so I then changed fatigue effect/recovery to try to give more ice time to top 6 players. I realize penalties and therefore special team play would affect this greatly but I'm playing with out-of-box tuner with very few penalties being called. This was not a controlled test and just something I happened to notice.
Bottom line: Fatigue effect/recovery MAY affect ice time on auto line change. This would need to be tested to confirm however, unless, of course, you've already tested this.