Ele. Dryer takes more than 2-3 cycles to dry

My dry seems to get hot but not hot enough to dry the clothes in the first cycle. It takes 2-3 cycles to dry the clothes. I don’t know if it is a thermo sensor or the heating element. How can I check to be sure?

The most common cause is a dirty or malfunctioning vent system.

Undo the dryer from the exhaust
Run a load
If the load dries correctly then you have a vent problem.
Clean/check the vent system. Make sure the outside louvers open fully.

If you do not want lint in the house.
Take a pair of pantyhose, put one leg into the other and attach this to the dryer exhaust.
Leave enough room behind the dryer so it can blow out like a windsock.
Run a load.

Both the above will allow you to check the air flow and temp.
Also the above is NOT recommended for a gas dryer due to possible carbon monoxide problems