the normal rule is -1/+3, but there is a 50 level cap on the usual rule.
when max of offense/defense reaches 50 the rule gradually transitions to -1/0
If your offense is 45 you get 44-48 camps
if you have a 48 offense you get 47-50 camps
if you have a 49 offense you get 48-50 camps
if you have 50 offense you get a 49-50 camps and further on it becomes -1/0
so for 51 offense you get 50-51 camps only
etc
for 62 offense you get 62-63 camps
then the cap is 65 later on even if your offense is 66.7, you get 65.0 camps
there might be servers where any of these rules can be different given some of the recent patches though