have you seen these topics?
- GRD multilook (number of looks)
- Equivalent number of looks (ENL)
- Number of looks (multilook) is there a range?
- Multilook and pixel size of SLC IW Sentinel 1
There is no ideal or “appropriate” number of looks, because it depends on your application. For example, if you want to analyze agricultural fields, you might reduce the resolution to 50x50 m per pixel to reduce noise in your data and also the data volumes, especially when you are working with large areas. In contrast, if you want to analyze fine-scaled features (e.g. roads), a small number of looks should be chosen to conserve the information present in single pixels.
Please also note that GRD data is already multi-looked to a pixel size of 10x10m.