There is no one-size fits all account structure. It’ll depend on the business type, budget, and other factors.
Assuming an online store with a small budget, I would not be running more than two shopping campaigns (maybe even one). And if you’re running P-Max with asset sets I wouldn’t bother with display as a separate campaign or included with search. Display would really only be good for branding and I’d start with Discovery for that or honestly, paid social.
As for search partners, that’s not a “campaign” but rather just a setting.. we usually test it for a month or two and then disable it if performance is subpar and we’re able to easily spend the budget elsewhere.
A larger account, think $10K/day and up might include dedicated campaigns for video, display, discovery and more shopping campaigns, specific to different product categories. You could also have regional campaigns and/or dedicated campaigns for search remarketing, etc. The more budget you have the more campaigns you’ll typically have. Otherwise, you want to integrate as much as possible for efficiency.