This paper extends the Tulipa energy system optimisation model by incorporating start-up and shut-down capability constraints formulated for Tulipa's fully flexible temporal resolution. The impact of adding these constraints for thermal generators is assessed using a greenfield case study with 7 European countries. Results show that including these constraints increases computation time, but they more realistically represent generator behaviour, which also results in a higher objective function value. Cases where the resolution of assets is not a multiple of the resolution of flows result in uniquely long solving times. The investments, as well as the unit operation trends remain similar on a high level. Batteries are utilised to improve the reduced flexibility, and units with the most flexible start-up/shut-down capabilities become used slightly more often, while the opposite holds for those with the least flexible capabilities. Units also tend to be turned on and off less often. This research contributes to understanding the trade-offs between model complexity and runtime in long-term energy planning.