That's a good question
@FLHXHS The C2C ride has some interesting facets. For the US version it's common for riders to ride a BBG, sleep and finish it up after the rest stop in a hotel. The Canada version is longer with more time allowed and lower speed limits.
Plan your route. Plan your stops. If you're going for the Gold version you have approximately 15 hours off the road to plan in, at maximum. If you ride 16 hours, rest for 4, you're sleeping 3 times in the process. That's not un-reasonable, but it's also not most people's normal sleep rhythms either. Ideally you need to find a rhythm that fits with your normal sleep pattern. Do you know how many hours you normally sleep in each sleep cycle? A sleep cycle is from laying down, going thru REM sleep into D state, (deep, non-dreaming), and back into REM before waking. Most of use do this multiple times in a normal 'night's' sleep. I sleep in 3 hour cycles. When I did the Ten-n-Ten rally I rode 20 hours, was off the road for 4 and slept for 3 hours, then repeated. I never set the alarm clock, just got up when I woke up.
You need to identify what your sleep patterns are. And consider the overall time frame you want to aim for. I've done a lot of endurance rallies and know I can usually ride continuously for 30-40 hours with an Iron Butt Motel nap if needed. Based on that, I could not do a C2C w/o a solid sleep break. I don't know what works for you, but suspect 16 hours on the bike will not put you ready for sleep. For many, that's about what a SS1600Km ride would take. It's roughly 5860 kms coast to coast staying in Canada. That would leave you about 1100 km on the last segment of your ride. When you leave is going to play a significant part in where/when you stop. And how easy it will be to get a room. Trust me, an actual bed and shower does amazing things for sleep quality and for establishing a repeatable rhythm.
Based upon your suggested 16/4 pattern, if you started at 0600 hrs, you would be off the road at 2200 hrs the first night. 10 pm is not an un-reasonable stopping time. However, that puts you back on the road at 0200 hrs, (2am), and off the road the following leg at 1800 hrs, (6pm), when it's still light and you likely won't be able to drop off to sleep. Up again at 10 pm for the third leg putting you in a position of riding thru the entire night period which is more stressful and fatiguing. That ends the third leg at 10 am. A nearly impossible time to get a room unless pre-planned and far outside any semblance of normal sleep routine. And now you're starting the final leg at 1400 hrs, (2pm), and need to ride for another ~1100kms to finish.
I would suggest that instead of looking at it from the standpoint of how many hours you want to ride and sleep, you look at it from a more traditional standpoint of when do you want to get on the road and when do you want to get off the road?
Some prefer to ride darkness at the beginning of the day and quit for the day at nautical twilight or within a couple of hours after. Darkness naturally brings sleep to many of us. If you started at 4 am each day and rode until full darkness, give or take, with a pre-planned hotel stop you could get more sleep between legs. 4 am to 10 pm is 18 hour days. Sleep/off the road for 6 hours gives you plenty of time for a shower and sleep/eat. Back on the road at 4 am. A repeatable rhythm. You need to decide how far that time frame will get you each day and what your goals are in terms of doing the C2C in 75 hours or 90 hours. It's not a bad thing to plan for 75 hours with the fall back of still completing it in 90 hours. A C2C is not a walk in the park for either time frame.
Just my thoughts on this. It's your ride and your plan. The old saying is "Plan the Ride, Ride the Plan... until you re-Plan."