Usage of Target and Maximum Bitrate with the H264 Codec in Premiere Pro
You seem to have a good grip on what these parameters are all about.

The target bitrate is what the encoder tries to average throughout the video.

The maximum bitrate is the roof for how high the bitrate can go. How high it can spike.

It's a good idea to leave a substantial amount of headroom, 5-10%, between the target and the maximum bitrate. 

Best of luck!