Is the default input size of the model performance best?

[seon-creator]

Hi, I'm using mmpose for training model.
When I see the models like top down, input size 256x192 or bottom up models input size : 512x512
for example I'm using these.

mmpose/configs/body_2d_keypoint/dekr/coco/dekr_hrnet-w32_8xb10-140e_coco-512x512.py

mmpose/configs/body_2d_keypoint/topdown_heatmap/coco/td-hm_hrnet-w32_8xb64-210e_coco-256x192.py

So, my question is like title, Is the default input size of the model performance best?
And another thing is why bottom up models input size ratio is 1:1?

I changed bottom up model's input size 256x192 and train it.
After then the inference result is not so good.

My data img's size is 1488x837.