Do smart or programmable thermostats actually save money?
I only worked in the commercial/industrial field of steam and hot water boilers so take what I say lightly. Here is what the heating engineers told us; if you can set back the thermostat or reduce the buildings temperature for 8 hours or more then there is a cost savings and if you can't it is probably not worth anything. One of the main problems with temperature reduction was that when the room temperature was brought back up to the comfort level, the furniture, desks and everything in the room was still at a reduced temperature. If you were to use the furniture or items in the room, the room still felt cold.
I have a friend that is a lot younger than I am and he changes temperature many times a day. When I go into his home I always take a sweater, In my house I set the temperature to one setting for the winter and one for the summer. We have like houses and heating systems and our heating bills are about the same. My house is always more comfortable than his.  My 2 cents.