It really depends on what the goal of a campaign is. When playing with mods I often just try to complete the mission tree and that's that (Anbennar, missions expanded)
Playing optimally is often not all that fun to be honest. I mean, it's stretching your nation to the limit, juggling truces, juggling aggressive expansion, being constantly at war, often with no treasury, and mercs and lack of manpower (especially earlygame and playing as a Horde), while it can be equally fun to just sit back and make your nation prosper. At least it's more 'chill'.
But, to each its own. It's a sandbox game for a reason, i.e. you set your own goal and abide by your own set rules.
In general, I like playing somewhat optimally, but always add in my own spice. For example, I usually take one 'wildcard' idea group early in my run to facilitate a certain way I want to play that game. In my three mountains run for example I took innovative ideas as my second group (after exploration) and kept it until I reached 100 innovativeness. It worked out decently well in the end. In the current patch I'm testing out opening with espionage ideas, but I'll often taken subpar ideagroups to make my run more flavorful. Trade ideas (them policies) is my personal favorite 'subpar' ideagroup.