Your dryer has three places where lint can build up: the screen you empty before each load, the housing and duct behind the cabinet, and the exterior hood where the air leaves the house. Each one often has a different owner, and that is the first thing to settle.
Start with the screen
Pull the lint screen before every load and clear it by hand. Lift off the lint, then run a finger along the screen edges, where a thin film from dryer sheets can form. A coated screen lets less air through than the lint you can see, so drying times creep up before anything else changes. Keep the screen in its slot whenever the dryer runs. A dryer running without its screen sends lint straight into the cabinet.
Check the housing and the first run of duct
Once a season, or whenever drying starts running long, pull the dryer out far enough to reach the back of the cabinet and the duct connector. Look for lint packed around the connector and the blower housing. A vacuum with a brush attachment handles most of it. Do not run the dryer with the lint housing open.
Then look at the duct itself. The run should be as short and straight as the room allows. Each bend and each length of flexible foil or plastic duct slows the air and gives lint a place to settle. Rigid metal duct is easier to clean through and holds its shape. Flexible duct that has been crushed behind the dryer restricts airflow even when it looks connected. If the duct is pinched or sagging, the repair belongs to whoever installed or maintains the vent, so write it down before you move on.
Walk the exterior hood
Go outside while the dryer runs and feel for air at the hood. The flap should open freely and close when the dryer stops. If the flap sticks, or the hood is blocked by leaves, a bird nest, or a drift of lint, the dryer works harder than it should. Clear the hood opening and confirm the flap moves by hand. Many vent covers include a screen, so check that as well.
Read the drying time as a gauge
Keep a simple note of the load type, the cycle, and how long it took. When the same load starts running longer over a few weeks, airflow has changed. That is your signal to walk the whole path again. You do not need a meter for this. Your own log tells you more than a guess.
Name the owner before you need help
Decide who empties the screen, who does the seasonal housing check, and who reaches the exterior hood. It might be you, another household member, or a service visit. Write the names inside the laundry room door or in the folder with the manual. If a technician is needed for duct work, ask them to record the duct length, the connector type, and the hood condition in the service record.
What to compare when you plan the next dryer
When you reach the planning point for the dryer itself, the vent is part of the comparison. Measure the existing run and note the duct material before you shop. A new dryer connected to an old duct brings the old airflow problems with it. The dryer's page on this site gives typical service life and planning notes: Clothes Dryer: typical service life and when to plan.