Q:

More energy than normal - should I push myself?

Somedays (like today) I feel literally like I could move mountains! Is there any harm to pushing yourself harder on these good days? Just likes it's okay to slow down on the low energy days (I'm talking about going from 5 sets to 7 to 8 sets).

A:

If you want to increase your overall time under load (which based on other posts of yours is a strong possibility), this would be a good time to increase the weight.  That way, on your low energy days you'll already have built the base to keep the higher weights.

Why not go up by at least 5lb in all your lifts, and keep at least the same sets/reps you've been doing?

The arguments for and against the extra sets really depend on your goals:

Body building is trying to increase time under load, which usually emphasizes more sets/reps
Strength training keeps the number of sets/reps constant while progressively adding more weight
Lifting to failure makes the time after the gym much less pleasant--which tends to demotivate people.  Might not be an issue for you.
More weight at the same sets/reps is more load which also means more muscle.  I tell you, it doesn't take long before it becomes really challenging.

