The majority do not receive lvl 12 spies so I wouldn't say everything. As long as you have a higher level than the enemy, you'll be ok. On the rarity that they have level 12 spies then yes, hopefully you get them as well or you can also ask an ally state who may have lvl 12 spies help you out. Again, this is only for just the savings and market activity parts of the OSI. As long as you have more spies, you will still see their overview.

Savings and Market activity information is not game changing.