During Race against Time event, the Main city's recruitment time decreases by 20%. So it is best to use your heroes that have the skill to reduce recruiting time of certain troops.
So I am using Lancelot's skill to quickly produce Royal Knights.
Expected time needed to finish recruiting shown here when you decide the number of recruits.
The time needed to complete after minus 20% and minus 40%. Then finish immediately by using speed ups and continue the next batch until you get the Sanctuary level 25 as a reward for completing the recruitment of 20K soldiers. Attack the sanctuary immediately because anyone else attacking it will get the same good loot as we the owners do.
Like I do 😬😬
So I won't be aiming for tier prize this time. I just want to recruit as much Royal Knights as possible. You have to get onto the Leaderboard to get good prize.