There is of course some exceptions to this, if the consultancy firm you has an IP that you need to use for their service, or they have specific industry experience directly related to your project, it is always advisable to meet with the consultancy firms you are considering. There are many methods of doing this, depending on the size and scope of your works, you could take a longer, or shorter approach as outlined below. Once more, it will probably be a mix of the below.
A strong consideration is the size of the project and justification of the length of the tender process. A longer tender process will invariably require a higher level of speculative work from the management consultancy business. The effort level and length of opportunity should be balanced and proportionate to the scale of the overall project. Another major consideration is to ensure that the consultants who will be handling the project are in attendance at all face to face meetings. You and the business will be spending a large proportion of time alongside the consultants, it is important that you are comfortable with them.