I used to play another game which had a similar system as convoy, though it was cross-server and was open 24hrs. The only difference was there was a specific event on the day which you had double rewards. There you had 4 convoys and 2 chances for plunder, also a guard friend like this one, but the lvl restriction worked for you and your guard. Ex. if you were lvl 70 only ppl close to your lvl or 20 lvls ahead could attack you, same for a guard who was lvl 30, your convoy could only be attacked by ppl close to your guards lvl. Also if you were plundered you got 60% of convoy reward.That's how I remember it worked. But I don't like the way this game's convoy works cuz basically you get less than half of what the plunderer gets when they win, 50c vs 15c is not balanced at all.