True mustafagander. Even less, and they do change for QNH less than 1013, and cold temperatures. Some modern ATIS are just METAR announciators and do not have TL info on them. Other places are 7000ish. Elsewhere you could be crusing at FL70 and enter TMA from a side and set QNH for this, as in the TMA TL is FL120. Weird stuff.
Hence the other approach to switch ASAP works the best. To support the risk assesment case, descent to altitude from above, let's say, FL180 is seldom the clearance. Typically last assigned FL is around 120 (whether or not you get to maintain it), mostly because of ATC sector fragmentation which is due to national borders and capacity demands.