Harrying enemies is good if the player has nothing better to do at the time (i.e., no more targets) and the target has fighting ships. Otherwise, it is tedious even with a burn speed of 10+.
@ Kipcha: Cerberus is not very good at fighting (big ships or whole fleets) without serious optimization, and I dislike ships with no defense system (i.e., shields or phase cloak) because there is much less margin for error. Cerberus also has burn 6 which, while not too slow, is slower than the Wolf pack I use. I rather optimize a ship I enjoy piloting. Also, I do not fight merely frigates, I fight everything. As I post elsewhere, I often use a single Wolf to solo most pirate fleets, and bring in the three or so extras for really troublesome fights. So far, I have only seen a single non-D Hound, which I promptly bought. My game has been stingy with them. I have seen plenty of (D) Hounds (with Degraded Engines), which were useful early in the game when I needed the slow starter Hammerhead; but late game, I do not need slow frigates anymore except as emergency cargo transport during an event (namely food shortage).
Also, small fleets are good for access to enemy non-pirate bases. I plan to upgrade to a Medusa (which can solo everything), declare war on some factions, then farm defense fleets to accelerate XP gain.
My overall point on this topic is for some fleets and playstyles, carefully management/toggling of Augmented Engines is optimal. Add hullmod, remove it when overburdened, add it back once the burden is gone.