It makes sense to put sudden tempo changes in one shot tracks. However, when this is done the tempo changes are ignored.
On a track, add a BPM effect and set the tempo to 80BPM
On another track, add a BPM effect and set the tempo to 120BPM
Show that, when alternately activating these two tracks (only one should be activated at a time), the tempo changes as desired.
Now change both tracks so that they are one-shot tracks (run mode = trig).
Now attempt to change the tempo by activating each track in turn.
The tempo changes do not occur beyond the first change.