It is likely nice to know what you did before but if it occupy too much place in your mind it can actually hurt you. Especially if you have different workouts or if some variables go up while others go down.
Let me give you an example.
SESSION A you did...
Bench press 275 x 4 sets of 6
Incline bench press 225 x 3 sets of 8
Cable cross over 65lbs x3 sets of 10
SESSION B you did ...
Bench press 295 x 4 sets 6, 5, 5, 5
Incline bench press 225 x 3 sets of 7,6,6
Cable cross over 65lbs x 3 sets of 12
How do you interpret that? Will you be pissed that your incline press went down? Of did you consider that the fact that you lifted a lot more weight on the bench created more fatigue, decreasing performance on the incline press?
Not to mention that on any given day you might progress, regress or stay the same. I have been saying for years that under the best circumstances, out of 10 workouts you will...
Progress in some way in 6
Stay at a similar level in 2
Regress in 2
Now if you overanalyse everything and stress about little details you might make that ratio a helluva lot worse