I’m assuming based on your question that you are using a free SimpleLogin account. If you have a premium account, you’re much better off making a unique alias for every account rather than grouping.
How you group accounts for your aliases really depends on what kind of accounts you have. I would suggest that “high value” accounts (banking, crypto, government services, etc.) each have their own alias or share an alias with a small number of other “high value” accounts. A larger number of “low value” accounts (forums, newsletters, etc.) can share a single alias (assuming you are okay with the identity of those accounts being able to be correlated to one another).
You use AnonAddy’s free plan in addition to SimpleLogin’s to get even more free aliases.