If multiple users are going to enter data into the same Table at the same time, you can run into Record Locking issues.
If you do happen to run into that, you may want to have users enter their data into a temporary Table (in the frontend). Then, when they are done, they can transfer everything to the main Table using an INSERT query or VBA.
If you are serving 150 users that will all be using the database at the same time, you might also want to look into using SQL Server (or another server-based RDBMS) to store your data. You can still use Access for the frontend.