We don't block IP's for every invalid click. We determine IP's to exclude based on the level and type of threat and exclude them for an amount of time appropriate to that threat level. For example an IP we deem to be a low/medium threat we may only block for a couple of hours/days, whilst something we deem as a high threat could be blocked for a longer period of time.
Our machine learning algorithms are always working to determine how much of a threat an IP is, ensuring your google ads account is always protected. We also monitor the behaviour of the users and their propensity to convert, we use this quality score to ensure that we will not block IP's that valid quality users are connected to.