"I have a doubt If I dont put spanning tree portfast command for each interface, Will there be any problem even though by default pvst is enabled on SW?any loop issue something like that?"
If you don't use portfast you have your best (about 100%) protection against allowing a L2 loop.
However, not using portfast, where it should be used, has two major effects. First, it may take multiple seconds (up to nearly a minute) for STP to allow the port to join the network. (The common impact of this, DHCP hosts often will not acquire their DHCP IP.)
Second, TCNs are needlessly generated for edge ports. These can be rather impactful to operational performance. So much so, the question often asked is, if we have no intentional L2 loops, do we need to run STP at all? (BTW, the normal answer is, it's recommended to run STP to preclude accidental L2 loops.)
Also BTW, if you have portfast enabled on a port that does create a L2 loop, Cisco's implementation will try to block the loop.
I suspect PVST is still the enabled default because it was Cisco's original method to deal with L2 loops and it's so important to avoid L2 loops. Portfast is not enabled by default because it adds some risk, if misapplied, to allowing a L2 loop.
Depending on the platform, there are newer and better L2 loop preclusion technologies than PVST. Also with the advent of L3 switches and Etherchannel, intentional L2 loop designs can often be avoided.
As a general recommendation, use rapid PVST with portfast on edge ports.
Lastly, your OP appeared to only ask why the section command returned the results it did. My original reply answered that, but it appears what you were asking was the purpose of portfast. Many replies answered that too.
