In the past I was always for more scouts too.
But with monitoring alot of province data right now. I think it is uneccesary.
The last 4 provinces I scouted/conquered were avg. in ring 11,5 with an avg. scouting time of 48,5 hours, avg. negotian costs for the whole province of 52k per tier, but I fought 5 encounters in avg. succesfully, so remaining negotiation costs of around 20k per tier, my avg. lost troops took 46,2 hours of training (some troop losses were avoidable though, because I lost some squads trying hard to fight 2 encounters that I negotiated in the end)
On an active day I produce around 20k goods per tier, a little bit more on very active days and a good bunch less on not so active days. (And I think I'm really close to the possible maximum without premium buildings and quest dependence)
So with a second scout I would probably run out of troops and/or goods in the future and I think it would frustrate me more to wait for troops/goods, before I can conquer another province, then it is now with waiting 2 days for the scout, but being able to do the province smooth after scouting, without worrying about something.