Not really. You can be sampling at exactly Fs/2 but be off phase. If the detector and loop are decent it'll figure out which way to steer the phase without additional samples. It won't always be on the right phase, that's the point of letting it lock, but you don't, theoretically, need more samples to do it. The detector may be hard to sort out depending on the signal, but you don't need more samples.
It's common to do this with PSK/QAM signals, where there is only one sample per symbol. You don't ever need to sample higher than that from just a sampling requirement perspective and common detectors will lock the sampling clock quickly to the symbol peaks. Eric Jacobsen Minister of Algorithms, Intel Corp. My opinions may not be Intel's opinions.