A receive group list is just a list of talk groups. When configuring a channel in your radio, if you want to hear more than just the talk group you’re listening on, you will need a receive group list.
A receive group list can contain more than one talk group. If you want to be able to listen to several talk groups without changing channels or using scan lists, you can add them into the receive group list for that channel.
Some radios require use of an RX group list to hear anything. On most radios, if you leave the RX group list empty, you will hear whatever talk group is set to be the default for that channel.
Initially, my codeplugs had all of the talk groups for a particular time slot in one group list. The problem with this configuration is that it’s impossible to squelch or nuisance delete individual talk groups. Currently, I use scan when I want to listen to multiple talkgroups.