Scenario- We want to create sub-sites for all the project that we work on. We have about 1500+ projects per year, both big and small. Some may last a week and some may last a year. I would like to keep 2000 sub-sites under a site collection as per Microsoft's recommendation, so I will create a new site collection for the sub-sites when we are hitting the threshold.
Is there any drawback for having so many sub-sites under the site collections. In my opinion one major issue will be the management of the site when it comes to site permissions.
I would like your opinion here and see if there are any issues with designing project sites as listed above.