But will I “feel the benefit” ?

My granny used to believe firmly in always taking coats and jackets off the second one came indoors and not putting the extra layers on until actually going outside because we “would not feel the benefit”
Problem, it’s flippin freezing this morning so - do I put on a “proper “ Winter woolly as my instinct tells me to do, or should I struggle on with perhaps a T shirt under a lighter jumper or fleece , leaving the “big guns” for when the temperature is truly in single figures? Will I still “feel the benefit” ?
Oh first world problems.