Earlier (see in Brusov et al., Generalized Modigliani–Miller theory: applications in corporate finance, investments, taxation and ratings, Springer Nature, 2022) we have conducted the analysis of effectiveness of investment projects within the perpetuity (Modigliani–Miller) approximation (Modigliani and Miller, Am Econ Rev 48:261–297, 1958; Modigliani and Miller, Am Econ Rev 53:147–175, 1963; Modigliani and Miller, Am Econ Rev 56:333–391, 1966). In this Chapter the analysis of the obtained results on the exploration of efficiency of investment projects of arbitrary duration [within Brusov–Filatova–Orekhova theory (Brusov and Filatova, Financ Credit 435:2–8, 2011; Brusov et al., Appl Financ Econ 21(11):815–824, 2011; Brusov et al., Res J Econ Bus ICT 2:16–21, 2011; Brusov et al., Res J Econ Bus ICT 2:11–15, 2011; Brusov et al., Appl Financ Econ 22(13):1043–1052, 2012; Brusov et al., J Rev Glob Econ 1:106–111, 2012; Brusov et al., J Rev Glob Econ 2:94–116, 2013; Brusov et al., J Rev Glob Econ 2:183–193, 2013; Brusov et al., Cogent Econ Financ 2:1–13, 2014; Brusov et al., J Rev Glob Econ 3:175–185, 2014; Filatova et al., Bull FU 48:68–77, 2008)] is conducted.