If you are talking about AGC with modes like FT8, FT4 , the usual recommendation is to experiment with various settings on the rig and see how they impact varying receive conditions. K1JT's 2018 guide (https://www.physics.princeton.edu/pulsar/K1JT/FT8_Operating_Tips.pdf) says...
" Use the rig’s AGC or take care to adjust the RF gain control and attenuator whenever there are strong signals on the waterfall. Overload in the receiver and/or sound card can mess with any digital signal processing in your rig and on the soundcard including, WSJT-X’s decoding and waterfall display. AGC is the easy option, preferably on a fast setting. Consider using your rig’s filters too... "
