I have had animals invade my home once. Is it now more susceptable to more invasions?
Potentially, yes. That is why your wildlife professional should guarantee the work at no-extra cost, for a stated period of time. If during that time period, your attic is invaded again, the guarantee should allow that the offending animals will be removed at no additional cost. It should be reassuring to know that over time, the chances of reoccupation will diminish, which explains why the guarantees are limited to a specific length of time.