I find customers with a lot of sites (the sort of scale you describe for yourself) find the power of Templates a bit scary; yes, it's great that you can update a setting on that many sites, very, very quickly - but, as Spiderman rightly said; with great power comes great responsibility. 😁
Remember though that all changes are visible in the Organization > Change log - so could be just as quick to back out at the same scale/rate (maybe not so nice for firmware updates).
In such instances, maybe consider having 'a few' Templates, each of a scale that makes sense to you.
Template 1 - maybe with just my Lab Network bound - for initial testing
Template 2 - Ten guinea pig sites, I roll change out to second
Template 3 - 50 sites for further reassurance
Templates 4, 5, 6, 7, 8, 9 - each with max 100 bound sites, which I can phase the change through
A change in 10 GUIs still takes time, but a lot less than doing the same to 700 sites individually! It's also maybe simpler than API if you don't have in-house skills for that (or can't readily get them in from a Cisco partner).
You can have as many Templates as you like, so cut this to suit your needs (and bearing in mind Ryan's excellent advice - in particular that the Dashboard API is there to provide ultimate flexibility, if you need it.