The phrase "are usually very small" is correct and usable in written English.
It can be used to describe the typical size of an object or group in a general context.
Example: "The particles in this solution are usually very small, making them difficult to detect with the naked eye."
Alternatives: "tend to be quite tiny" or "are generally quite small".
Because the value gaps between similar financial instruments are usually very small and temporary, this type of activity typically involves trading in very high total nominal amounts.
Irrespective of location, erosion losses are usually very small from forestland or permanent pastureland, moderate to high from land planted with grain crops, and very high from clean-tilled orchards, vineyards, and land planted with row crops, as shown in the figure.
Cells are usually very small, but big ones exist and can weigh over a kilogram.
Estimates of wage elasticities for this group are usually very small, often not significant, and sometimes negative.
However, developing appropriate forecasting models for such systems can be challenging in their early stages, as the sample sizes are usually very small, and thus there is limited data available for analysis.
M.D.-Ph.D. programs are usually very small, so such organizations and social networks provide opportunities for women to meet people at other institutions, discuss areas of common concern, and learn from others' successes and failures.
The newly metamorphosed salamander is usually very small, and up to several years may elapse before it is sexually mature.
In liquids, glasses, and crystals that have a centre of symmetry, the change is usually very small.
Since the sampling period is usually very small, the integration (24) can be approximated as (25).
Since (|E_t|) is usually very small in real applications, the algorithm is still efficient.
But the depth of potential well d for the problem (1.1 - 1.3 1.1 - 1.3ly very small etc.
