The HOA lawyer probably inserted the language. A general principle in property law is that you must assert your right within a reasonable time, or you can lose it. A year is typical. Example: my neighbor build a fence two feet inside my property line. If I don't complain within a year, he is going to own that slice of my property
Depends on the state. Most states, it's going to be 10 to 30 years unless there is color of title. For example, in Louisiana, it is 10 years with good faith and just title; otherwise it is 30 years. Georgia, it's 7 years under color of title; otherwise 20 years. Texas, generally 10 years, with 25 years in some circumstances, and a shorter period when suit must be brought after discovery.
It can be a surprisingly complex and fact driven situation.