Upgrade path to TF 1.* - recommendation for live envs

Hello,

Want to learn from your experience/recommendation regarding upgrading of existing envs’. Our TF project is constructed from ~15 TF modules which each have his own release cycle.

For real life use cases of products/application that already deployed and running on environment that built from TF 1.14, would you ask to “re-apply” for all TF modules while the change is only for TF engine ? what will be the best practices so if tomorrow this running env will need additional capability ?
Should we ask for only “plan” ? or even to have kind hybrid solution ?

For new env or for tests env the patch is clear, problem here for production evs risks.

Thanks

anyone have experience with large scale envs and upgrades