Washing bed sheets along with the clothes is not a good idea. Due to their giant size, throwing these in with the set of clothes would mean that you are preventing the washing load from washing properly. The clothes would get trapped on the sheets and would not have a chance to get cleaned or washed easily. Since these would not agitate against other clothes and they would simply be rinsed. Similarly, the drying time on combining the sheets along with the clothes means that the drying time would be quite long and the same gets trapped between the sheets.
So, if you have a machine with a detergent dispenser then you need to follow the machine used as per the manufacturer's instructions. Some of these may work better with liquid detergent and you may need to make minor adjustments using the powder variants. On the other hand, if you are using detergent pods then you need to follow the appropriate instructions for the washers and detergents. This is because in certain cases, the water flow may not be as sufficient as to dissolve the pod. The same needs to be placed along with the sheets inside the washer drum.
Ultimately, understanding the type of sheets, your washing machine, load-bearing capacity, etc. you may opt to wash your sheets separately. For instance - polyester blends are best used with warm water while cotton ones can bear hot water. By opting to wash all these sheets separately, you ensure that the same is washed and cleaned properly.