If you are talking about soil blocks you make with a block maker, there are pros and cons with homemade blocks. The main reason for making horticulture blocks is when you need a bunch (100s). One of the pros is that the soil you plant in will stay the same and no transplant shock to the outdoors. One of the cons is they can compact too much or fall apart before the plants are ready for transplanting. IF you have trays for the blocks and the blocks are going outdoors they are a good choice.