I change tires for my bikes much more often than before because my RITCHEY outback has 700×48mm maximum tire clearance and it’s fun to use different tires for different terrain.
・Center slick tires (38 – 42mm) when it’s paved/unpaved mixed
・Knobbed tires (up to 45mm) when it’s only on unpaved.
That’s how I choose tires and it’s fun to think which tires will fit the best. I don’t use tubeless tires by the way because it’s annoying to clean sealant.
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Well, topic here is not thick tires actually. Frankly I’m not satisfied with 38mm tires for my commuting since I go for a ride just a couple of times a month. I had been using ULTRADYNAMICO’s cava race tires but I felt them a bit thick and slow on my paved commute road. The rolling resistance is low compared to knobby tires since cava race is almost slick but I still felt some resistance (maybe because they are thick in the end). Although, I love how ULTRADYNAMICO’s race tires ride smoothly because of its thin casing.
Therefore, I wanted the same tire but thinner so I swapped from CAVA to CAVA. It got much thinner from 42mm to 33mm.
cava race tire (700c/42mm) ↓
cava race tire (700/33mm) ↓
cava race tire (700c/42mm) ↓
cava race tire (700/33mm) ↓
Some might mind the gap in between the tire and the frame but I don’t because I prioritize how bike rides.
First of all, since this 700/33mm cava is made as a classic on-road race tire by Ronnie and Pat, it doesn’t ride so good on unpaved terrains. Also you can see that the tread pattern on 33mm CAVA is even smaller. In general, race tires are getting thicker but the CAVA weighs as same as them and even better ride. 
It doesn’t look too skinny when it’s actually running.
One last thing I want to tell you is that you should try listening to the slipping noise on very fine paved road with any CAVA tires, it’s awesome.
