Single system prompt vs multiple prompts in a single query

Recently came across technique called “post-prompt” (the last message in the query) and found it to be very useful to improve obedience to “last-minute” instructions.
Meanwhile, I tend to add other system instructions in between while compiling my query, e.g. current date/time, availability of human agents, etc

Now, tried to inject another system message before context to pay attention to specific details in context (to avoid assuming and inventing) and it seems to be ignored.

Question: what are your observations/experiences regarding multiple system messages scattered across query? Do they tend to improve or worsen model’s obedience to instructions?