Is it possible to use LOTO procedures in all electrical and mechanical repairs? And if not how can you control the risk in such cases?

Yes, you have to use any LOTO procedure for control of Hazadous energy.

OSHA regulations29CFR1910.147 clearly defines the requirement and implemetation.

By not following the LOTO procedure, one Layer of Protection is reduced which is against the safety of the personal and equipment, also the Risk (likelihood x Consequences) becomes unacceptable as per Risk matrix.

For controlling the risk in the absence of LOTO, a proper risk re-assessment is required by a competent team, and their recomendations should be approved by Management before bypassing as LOTO. or a Management of Change (MOC) procedure can also be adopted.