Hi Zaman,
What I mean by this is that for a single flow, the router always selects the same interface no matter the hash algorithm you use. The advantage of using a hash algorithm that uses more parameters is that you will have better load balancing since different flows will use different interfaces. For example, if you use a hashing algorithm that only includes source and destination IP address then it’s likely that the following flows will all get the same result and use the same outbound interface.
Here’s a quick example, let’s say we have these flows:
192.168.1.1 > 192.168.2.2
192.168.1.2 > 192.168.2.2
192.168.1.3 > 192.168.2.2
192.168.1.4 > 192.168.2.2
192.168.1.5 > 192.168.2.2
192.168.1.7 > 192.168.2.2
192.168.1.9 > 192.168.2.2
If we had two outgoing interfaces, it would be nice to see 4 flows on each interface so that we have some load sharing. However in reality, it’s likely that the flows get mapped like this:
INTERFACE 1:
192.168.1.1 > 192.168.2.2
192.168.1.3 > 192.168.2.2
192.168.1.5 > 192.168.2.2
192.168.1.7 > 192.168.2.2
192.168.1.9 > 192.168.2.2
INTERFACE 2:
192.168.1.2 > 192.168.2.2
192.168.1.4 > 192.168.2.2
In this case, interface 1 gets the most flows. By using a hashing algorithm with more parameters, the chance that each interface gets 50% of the flows increases. Still, this doesn’t consider how much traffic each flow has so it’s more like “flow” balancing than load balancing 
Per packet load balancing does evenly share the load, even though the packets belong to the same flow yes.