You are right. "Permanent home available to him" is the first test that tends to fail.. then you are left with CVI (centre of vital interest). If you spend most of your time in one country, your CVI is quite clearly there...unless there is strong evidence proving otherwise
Staying 183 days or more in a new country supports the claim that the CVI︉ is there.
183 days stay is actually more important for employment purposes. If you stayed︊ in one country for 183 days, then at least you can be sure your employment︋ income will not be taxed in another country where you stayed for less time.
At the end of the︍ day, tax authorities can also deviate from the law and act opportunistically, claiming your tax︎ residence. Then it's up to you to prove them otherwise.
Two countries can also interpret️ the tax treaty differently. In this case, MAP (mutual agreement procedure) helps, which you, as a taxpayer, need to request, e.g., to claim for adjustment.
The MAP is the mechanism that Contracting States use to resolve any disputes or difficulties that arise in the course of implementing and applying the treaty.
There is no such thing really.
Countries can interpret DTT differently, both claiming your tax residence based on a DTT.
Then you have MAP to sort it out, which can further end up in arbitration.