If you have a number of little jobs that need doing on your vehicle then it is often more cost effective to get them all done at the same time. Not only will this save you on fuel trips and possibly costs of using other transport whilst your car is in the garage, but you may find that the labour cost is reduced. This is because part of the time a garage will charge for is getting the vehicle up on ramps, test drivig it, removing covers and wheels etc. If the little jobs require this to be done then and you book them in at separate times then you may be payig for this part of the repair over and over again.
If a job needs doing and it is urgent or making the vehicle unsafe to drive then you should not wait for other little jobs to come up until you book it in. In this instance ask the garage to have a look over the car whilst they have it and advise on anything they see that may require work doing to it in the near future. This will then allow you to decide if you ask them to do that at the same time or make a note and book it back in at a later date to carry the work out.