For me this question has big impacts on corporate security. Consider the difference between:
- You can bind a spirit, then have a (carefully researched, worded and reviewed) command that would keep a spirit on guard duty duty until something happens. Perhaps you spent 3k on reagents and used up a day's time (plus possibly medical leave) for the summoner to get some number of services, but that spirit may well be staying on guard duty for the rest of the life of the summoner (assuming a few hits and it is guarding somewhere fairly quiet).
- That same spirit that took up most of a summoner's day to bind (and possibly more to recover from binding), is only good for maybe a couple of days (at half a day per service). You've drastically cut what else the summoner can do, and are spending ~50k in reagents per year per bound patrol spirit, to let the summoner have up two spirits instead of one, have one of them harder to banish,
In the former case, you can expect bound spirits in a fair number of warehouses, lower security office spaces, etc. (there are still limits based on how many spirits a summoner can have in place, so they will still be in places where security is non-trivial, but lower than otherwise). In the latter case, they will more commonly be kept in reserve, active patrolling would be done by simply summoned spirits or watchers in most cases, with patrol by bound spirit being saved for places that are important and remote, or really importantand in general the number of patrolling spirits you would encounter would be lower.