Hi, Nicole.
This confuses many new sitters. I've posted this response before, but for your ease of access:
think you can offer whatever service you are comfortable offering to your client, as long as the expectations are clear on both ends.
You could, offer house-sitting as an overnight service. Especially for bookings of more than one night, I would ask the owner what, if any, additional work needs to be done to maintain the house during the stay. I always make sure to take out trash, wash any dishes I use, etc. But I also have clients that need my help watering the plants or cleaning out their pool skimmers. You can always decline to provide any service you think is too much.
Then, pets that don't need overnight care would be booked as drop-in visits. They would book a certain number of 30-minute stays per day. They might still need certain house-care items attended to for longer visits, so be sure to cover this during a meet and greet.
For me, I offer house-sitting to clients that need over-night care. However, I also offer that service to clients that want me to drop in/out occasionally throughout the day, as if I lived there (without staying the night). These visits aren't always a full 30 minutes, sometimes they're longer/shorter. The owner might want me to stop in for two quick meals in the AM/PM and then a longer 30 minute walk around midday. I always get information about the dogs' regular schedules and stick as closely to that as possible. This is often more cost efficient for clients that have very low-maintenance dogs but need to be out of town for a bit.
If an owner wants exactly X number of visits per day, each 30 minutes long, and at specific times, then I do drop-in care bookings. This allows me to guarantee full 30 minute visits at the requested times.
You can do what's most comfortable for you. Just try to get as much information from the client as possible so that there are no miscommunications about what is expected of you/them.