I was dx'd in 1971. Had one shot per day for at least 10 years, perhaps as long as 15. We usually trusted my symptoms to tell me when I was low. My friends and their parents knew the basics. If I told an adult I felt "shaky" or "funny" they knew I needed food - juice and bread with peanut butter was the standard. Severe hypos where I lost consciousness were treated with sweet juice and/or honey. Later Mom kept glucagon in the fridge but there were only a few times that glucagon was used on me over the years. My younger brother was less stable so he had a few more glucagon shots than me.
There was no carb counting. Mom just knew that sweets were not permitted. I don't ever remember bolus doses when I was a child. I don't think the concept of bolus was explained to my parents until I was a teenager. Mom would notice if I was excessively thirsty and peeing lots. She would smell my breath - ketones cause the breath to smell sweet. If it seemed I was high we would use the Tes Tape. Dark green Tes Tape confirmed high BG and that meant I couldn't eat. We waited a while and it would drop, then I could eat. Mom never liked sweets so most of the food in our house was meat and veggies and dairy and bread. Dessert was a piece of fruit. For a treat there would be ice cream.
I learned all of this along with Mom. By the age of 10 I had a pretty good idea if my BG was too high or too low just by the way I felt. The Tes Tape was used to confirm. Later we used Chemstrips. They were cut in half lengthwise to double the number of tests (as mentioned in other posts). We started using blood glucose testers in the 80's. We grew up with minimal testing. I didn't like doing it so it was only done when I didn't feel right. My brother tested more because his diabetes was less stable.