Open Forum

From my experience, the answer to your question is likely to vary widely depending upon several factors, including the particular institution involved, the projected length of the capital campaign, and the schedule for completion of the construction/renovation work subsequent to the campaign.  In some cases institutions even meet their overall campaign goal, without obtaining all of the gifts that meet the specified criteria for naming opportunities.  In others they fall short but obtain financing to begin construction anyway while remaining open to later gifts.  Under either of these circumstances the institution can and often does defer naming the facility(s) in question, leaving these as future naming opportunities in association with prospective gifts at a later date. Once a facility like a gallery has been named for a donor, changing or removing that name - even many years in the future - can be problematic.  Consequently, it is NOT an action to be rushed or given away for an inadequate donation just because an arbitrary deadline approaches.  You can always use a generic way to refer to unnamed galleries (e.g. south gallery, special exhibit gallery, atrium gallery, etc.) pending receipt of a donation at the right level.  

For all these reasons, I would urge you to set ambitious minimum gift thresholds for your naming opportunities that support not only your direct construction expenses and associated soft costs, but also include a generous amount for an operating endowment associated with that facility.  Coupled with this policy, it would be prudent for any "deadline" you create for named gifts to be considered only a "soft" internal guideline and not something announced publicly.  That approach maximizes your institution's flexibility in awarding the naming opportunity.  If you receive a donation that meets your requirements, then you're in good shape.  If not, then you don't have to give away the honor for an inadequate amount that is likely to create problems for the institution in the future.  

To illustrate the value of this policy consider if your galleries being redesigned had already been "named" for their original donors.  Then you would currently be faced with the problem of how you recognize new donors supporting the planned renovations.  It is important to think strategically about what you will do with named galleries decades from now if there is a need to renovate or redesign them once again.  

In addition, you should make sure that you protect the institution's options regarding how long that name is associated with the facility.  You are probably familiar with the public perception problem that has developed in association with various museum facilities named for the Sackler Family, whose naming gifts were made possible by the proceeds from sales of opioids, driven by questionable marketing practices.  In at least some of these instances, the institutions in question have indicated that they have been able to change the name of the facility because their contract with the donor gave them that ability, given the adverse associations now connected to the Sackler name.  Involving knowledgeable legal counsel in the process of accepting named gifts would be another prudent step in the process.