They do, but only after the end of the year in which they've earned it.

Next year they're racking up the points, get to 60 nights or whatever, and then move on to the next chain (where they earned that status last year also).

So apart from the first year of non-status travel, they are permanently top level at whichever chain they travel to.

As for the original question - it makes sense for moderate flyers to TP run to gold in year 1, spend all their Avios in year 2 (if they can, anyway), drop down to silver and then focus on renewing at gold or silver in year 3 so that they get a sensible number of TPs for renewal the next year.