Impact of Time Interval and Firm Size to Beta

Just studied the characteristic line part. A bit confused about the impact of time interval to beta. Vol 4. page 268. It says “the interval effect depended on the sizes of the firms. The shorter weekly interval caused a larger beta for large firms and a smaller beta for small firms. … The authors concluded that the return time interval makes a difference, and its impact increases as the firm size declines.” Is everybody very clear about the above statement? In general, small firms have bigger beta (meaning bigger risk). Now, let’s add the time interval factor. Should smaller firm in a shorter time interval (say weekly) have bigger beta than the bigger firm in the same period of time frame? Would it be much simply to think no matter what time interval, smaller firms always have bigger beta than bigger firms? How do you interwoven these two factors when you consider the estimation of beta? Thanks.