I think the most important rule is:
Don't compare, do what works for you.
There's no competition or standards to meet.
For me personally it often works better to write something after each session when the impressions are still fresh, but of course time doesn't always allow that and then you have to decide to post or to play.
If I write later, I make sure to take enough screenshots and write down some short notes during or immediately after playing. If I lose connection to what my character went through, I find it harder to post.
You also don't need to keep the same level of in-character story or the same writing or formatting style throughout the whole report.
Of course, if that is your wish and what keeps you going, that's totally fine, I just mean I don't think it's a requirement.
Other people and myself have sometimes written one post like an in-character journal entry as if you were sitting at the campfire, one post as a full story thing, another post out-of-character with just a few commented screenshots about the tactics of an especially exciting fight, then a letter to a family member telling of a part of the adventure, another time just a quick bullet point summary of what happened and where we went, plus a few "postcards"...
What I mean is, it doesn't need to try to be a full story all in the same way, unless that is exactly what you wish to do. It's supposed to be fun, not a chore that adds extra stress.
In case of Icewind Dale, I can see how it would be more difficult to write about your character than in Baldur's Gate. (Have never finished IWD to be honest).
So in that case I personally would probably limit actual detailed character story writing to some bigger events and just insert some "commented pictures" snippets for the times between that, if that makes any sense.
It's also not mandatory to post the full run if you lose interest at some point.
The most important question remains what matters more for you: To have a consistent writing style and formatting, or to allow some variety.
How interesting it is to read and how smooth it looks should be secondary, unless of course you're a perfectionist or training for something.
It's a hobby, the most important part is that it's fun for you, either as entertainment, as a challenge, or a motivation to keep you going.
