We only recommend engaging multiple firms if you have an extremely challenging position to fill, such as a position that’s located in an undesirable location or if the required skills are very rare. Just because you engage 3 firms does not guarantee you’ll receive three times the amount of candidates or three times the level of service.
Recruiting firms know or will find out when a search is called out to multiple firms, and they know their odds of filling the position are lowered significantly versus an exclusive search. If the firm has retained or exclusive searches, they are going to prioritize the retained and exclusive searches over the non-exclusive contingency searches.
In addition, the odds are pretty high that if you engage multiple firms for your search, multiple recruiters from different firms will be reaching out to the same group of candidates. This barrage of messages coming from different recruiters at different firms can send a confusing message to the candidates and ultimately deter the candidates from pursuing the opportunity.