I'm a bit like Trv in that I'm not sure I've 'got' the question, but ...
In some respects you're right Platinum ... there will come a time where whatever you want done to a city, that some tiles will simply not compete with others in any optimal combination that suits your strategy or predicament at that time.
Of course, as the game continues to develop, so too do your opportunities to increase your happy or healthy caps and/or make better use of improvements (e.g. through civics or technologies), and that 'useless' plains tile that you were unable to employ all of a sudden has real possibilities.
There's little point in using up valuable Worker turns in developing some tiles around a city that simply cannot use those tiles well in any combination, if other cities in your empire are working undeveloped tiles or require some other Worker activity. On the other hand, you should be mindful of growth opportunities (e.g. about to get Calendar for Plantations) and prepare your Workers for these changes so you can capitalise on them when the time's right.
Likewise, what might have been a good combination of tiles in the Medieval Era might be reviewed in the Modern Era as the dynamics of the game have changed, so you should review the roles of your cities and see how tile improvements can be maximised in value in light of the new bonuses and how these all contribute towards your victory objective.