Total impact over several years

Hello: I am trying to estimate the total economic impact of a large number of companies during 2016-2020. I have their job numbers and using them to build the model(s). The assumption is that the job numbers will remain constant during this period. I understand that if I use the same job number for a company to estimate its impact in 2016 and in 2017, the impacts for the two different years are going to be the same in constant dollars. So, to estimate the total impact of a company during the 5 year period, can I just estimate its impact in 2016 and multiply by 5 (for labor income, value added, output, and taxes; I understand that I can’t add job impacts)? I would appreciate if you kindly let me know if the above methodology sounds correct to you. Thanks in advance. RB