Issues you have described refer to a local practice. You should combine local practices&requirements from opearting team, engineering team (process engineer + instrument engineer), management team (project manager, project consultant), and suppliers.
The same control principles may be solved opposite ways depending on local conditions.
E.g. I have encountered such option - a large distillation tower (~4x40m) had one level gauge on bottom and one hand-operated control valve on pump discharge to control liquid level in tower. An operator sits in a shed next to LG and does nothing other than 24/7/365 looking at LG and occasionally runing from LG to CV to open/close that. On the same application I have encountered 1 LG + 3 LT ESD + 1 LT DCS + Honneywell.
Good start for a newcomer is
https://a.co/d/gfTeiHv
https://bit.ly/46wX2YX
Edited by shvet1, 27 November 2023 - 12:07 AM.