Even with a SSD booting is not instantaneous. That's because there's CPU work involved to load the kernel, waiting time to detect and initialize hardware, verify configurations, etc. If it was just about the disk, windows would do a full load in about two seconds.
To your question as to whether "it would be good practice to occasionally do a full shutdown", I would like to point that doing a restart always does a full shutdown so unless you never use Restart you may be doing that already.
Also note that disabling Hibernate, a common "tip" for Windows 7 to save SSD disk space, also disables hybrid shutdown/fast boot.
So if there's no downsides to fast shutdown (which is basically hibernation), does that mean that there are also no downsides to actual hibernation? – Pacerier – 2015-04-26T23:50:28.290
Nice article here explains the different boot types – Moab – 2015-04-27T00:40:41.857