Rapidly switching between the 2 mining modes ("mine for yourself" and "mine for developers") puts rapidly changing workloads and heavy stress on GPU. It noticeably shortens the GPU's life and causes problems and weird breakdowns.

Also the switching causes a considerable loss of connection time, when it's not mining for anyone (neither for yourself nor for the developer). This lost time can even be longer than the time devoted to developer mining. The more frequent the switching is, the higher the loss. 90 minute period is quite frequent, do this 16 times a day and it easily wipes out any hash rate advantage.

There should be a better way to support the developers. A 1-time license payment is much better.

Or, change the switching period from 90 minutes to 12 hours. For every 12 hours the developers get 7 minutes of mining time. This way it not only reduces the switch from 16 times a day to twice, but the developers will also get a more consistent payment (mining is better done continuously for an unbroken period of time).