No, st-yCRV rewards are not released weekly. Instead, they are accrued continuously over time. Yearn has implemented a "Mega Boost" to increase the yield of st-yCRV, which is one of the sources of rewards. In addition to this boost, st-yCRV also earns fees from veCRV and bribe yield in CRV. This means that rewards are always being accrued, and can be withdrawn at any time. For more information, please refer to the Yearn Finance Telegram channel at https://t.me/yearnfinance/269322.