Strategy to consolidate multiple fields across content types?
I can't say which is better, because it depends on what customization you intend to do in the future.

That said, generally speaking, if you have different content types that use the same field for the same purpose, you should choose to re-use the field across content types in the design stage; doing so would've saved you the trouble you face now.

How to consolidate multiple fields

First, create a new field on one content type.

Next, re-use the field on all the other content types you want to use it on.

Then, see this question on renaming fields for information about how to use SQL to copy the data from the old fields to the new fields.  ALWAYS make a backup before doing this; if you make a mistake in this step, you can break your site.

Now, you will have to fix your views, twig templates, and anything else that might be broken.  You can go to your exported config folder and search for the field names of the old fields, but I wouldn't change the config directly; I would use the config folder as a hint of what to change, and then update the values in the UI.  I'd do this because sometimes one setting changes another, and if you do it in the UI, everything should get changed properly.