Is combining timed sections from the same test to get a score as realiable as full pt score?

I take PTs every now and then, highest I have scored was a 171, which i scored twice in the last 5 pts i have done

But I also try to take one timed section on days where i am not taking pts, I took all the sections for PT 157 over the course of 4 days and my score from the scored sections equates a 175, can I take that as evidence of improvement?

its worth noting, my usual worst section, RC, was the first section I did in the sequence, so any section fatigue did not play a role in that, and also I havn't experienced back to back section fatigue as ever really impacting my scores because often later sections are either equal to or sometimes better than earlier sections