I'm aware of last investment feedback, but I'm not sure if (what the other person proposes) is going to happen, so here is my simply suggestion:

What about to:
1)Change 5 days to 4 days
2)Therefore change 5% to 4%
3)And finally, to be fair, change 5 credits to 4 credits.

Why ? Because this way, you could be able to invest every day at let's say 6 PM and you won't have to carefully count when will your investment end (re-count it to real-life time, be awake for example in night's time to collect and invest again).

You will simply invest and recollect money at the same time every day.

As it is now, you have to follow increments of 6, like (D74) 7 AM - (D79) 1 PM - (D84) 7 PM and then (D89) 1 AM again. Of course, you're not going to catch it without time loss, so every investment will slip with few minutes.