The guest races are designed to slow you down, you start increasing productions then you need to make extra kp's to keep up with productions so its just a cycle that will spin out of control if not managed correctly, after a while your portals will reach the cap and you are just sitting around waiting anyway.
Im already at the stage in Fairies with all guest buildings fully upgraded that i have full capacity on ambrosia and essence that im just waiting for kp. I've only been in fairies a couple of weeks.
You use the down time to produce the items needed for the chapter roads so they are good to go when ready. so really no need for an enchantment IMO
Then theres the storyline quests that ask you to build a certain amount of guest production buildings. if you use an enchantment you are probably thinking you wont need to build as many production buildings to save space, but this will break the storyline quests if you follow them. etc.etc..