configuration_group_id non-consecutive numbering

In my configuration_group table, the configuration_group_id's of the latest entries do not follow consecutively but have large numerical differences, as in the following image.

In particular:
40 Return Authorisation
41 Events Calendar
71 Zen_Colorbox
92 Manufacturers All About

I know this happened by testing a number of different mods which involved uninstalling-reinstalling the mod sql files, but what I dont understand is:

• whether the non-consecutive numbering is a problem and may lead to inefficiencies,
• whether I can manually change the configuration_group_ids directly in affected tables or is there another better way to do this (as the latest configuration_group_id may be hidden somehwere)
• how to prevent this from happening in future - what is the correct procedure for ensuring that upon uninstall the configuration_group_id is reset back to the last mod.

Up until configuration_group_id = 40, the database was zc 151, subsequent entries were made in zc154.

Thanks

This is not a problem - nothing bad happens because of gaps or higher numbers.